The Greens recently launched a campaign to remove Group Voting Tickets (GVTs) from the Senate elections. While GVTs may seem strange, they give us a unique chance for innovation that is rarely afforded to modern democracies. To remove it from our election process is tantamount to censorship, and thus reduces the potential good that Government can do, and diminishes the value of our Democracy.
In this post I will primarily respond to the Greens campaign, though I've written more about the exact mechanism of innovation before.
The form of this response is a comment on a reddit thread that began answering the question:
First I'll give you a little preface, then answer your question by tearing apart their senate reform argument .
This largely comes down to what you want government / the senate to be. I am building a minor party around the idea of upgrading democracy without permission (such that if it works, it's better than the current system: see nvbloc.org, soon to be voteflux.org). Group Voting Tickets (GVTs) allow for sophisticated and innovative ideas to come to the fore without a large primary vote percentage (which we want) and the worst case is we get someone random from the community. Therefore I like GVTs. In the absence of a really good idea it is basically random, like picking a community member at random. I think this is also a good thing. It's almost like an opt-in 'jury duty' for government and is useful for generating conjecture and criticism around legislation which would help to produce better legislation, since parties take a line, and a limited number of parties means a limited number of ideas.  
The greens document says (and I'm mostly going to respond to the headings)
1// IT’S UNDEMOCRATIC
Firstly, 25% of NSW voted for someone other than Liberal, Labor, or the Greens in the last senate election (source). The idea that there isn't demand for minor parties is plainly false. 18% in VIC, 24% in QLD, 19% in TAS, etc. That's more than one quota so we should expect, from pure proportional representation to have at least one minor party in each state provided that minor parties acknowledge that their expected return increases when they preference each other first which directly means that representatives of 20-25% of the population are knowingly trying to get in on chance because it's better than the alternative which is not having a say at all. What is more democratic? That, or forcibly breaking up cooperation to favour major parties.
Now, there is a strong philosophical point I touched on earlier, and that is that the voices of these minor parties, diverse and unique, are all points that new ideas, criticisms, and policy can come from. Having some criticism is better than having none, and it is easier to persuade a few members of the crossbench than an entire party. If we remove GVTs it disallows cooperation between tiny players and reduces the possible input into the parliamentary process. A system of democracy that reduces input sounds suspicious to me. I am interested in the best system of democracy, and that means that we need to take the best ideas. By reducing the set of possible ideas you reduce the chance of picking the best one since new knowledge and policy ideas are necessarily unpredictable. When groundbreaking ideas come along we don't want to miss out.
2// IT’S SECRETIVE
It's true that negotiations for GVTs take place in a fast paced and high pressure environment. While some parties (like the Pirate Party) attempt to 'measure' the correct preference order by polling their members, other parties take a pragmatic approach and try to maximise the chance of reaching parliament. Sometimes this backfires (because nothing is certain till election day) and a lemon is elected, but other times the new voice is quite welcome and refreshing. If we lose one we will likely lose the other and personally I prefer more voices, not less.
Preference order is made public 2 weeks before the election and there's time for research and planning. Most people don't care though, that's because we live in the real world. By identifying with a minor party voters are doing far more to influence parliament in a way they approve of then if they were to vote for a major party, simply because there's a chance they'll be heard. So even if you don't like it, this is the democratic process in action because at least a group of people get to have a say. By stifling these voices you just ensure they never have a say. Personally I think there's a middle ground (see voteflux.org / nvbloc.org for my plan).
3// IT PRODUCES PERVERSE OUTCOMES
Okay so the Greens think that because someone with less votes than them gets it before they do it's a bad thing. That's the gist, but really that's not true. They are denying the entire idea of preferential voting when they say this, because for their scenario to happen, it must have been the case that a very diverse group of people preferred someone else. Again, if you want to have democracy you have to acknowledge that there are other people and they might not want you there. By reducing competition the Greens are suppressing this, in violation of their charter (section on democracy).
4// IT’S TOO COMPLICATED
We support small parties and independents running for the Senate
They would kill small parties with this "reform". They would seriously wound FLUX (voteflux.org / nvbloc.org) for sure which means that a new innovitave idea would potentially never be allowed to happen. Just because it's complicated doesn't mean it's bad. What matters is that it allows for something very particular: measurable flows of preference, which most other systems of this diversity don't. We have a rich election and for that we should be grateful. Does a healthy democracy increase or decrease the number of opinions it considers?
Complexity is preferable if it produces better results. That's basically how technology works.
5// IT UNDERMINES THE SENATE AS A HOUSE OF REVIEW
What is more important to a house of review than a diversity of opinion and specialists of all forms? My only guess is that they are more interested in stability and permanence than really solving problems.
The simplest and most democratic way to fix the Senate voting system is to outlaw secretive preference deals by abolishing Group Voting Tickets. This takes the power over preferences away from political parties, and gives it back to voters.
Another way to phrase that last sentence is:
This takes the power over preferences away from those people motivated enough to form a party for a cause they care deeply about, and distributes it as far and widely as possible amongst a population of regular people, many of whom do not have the time, energy, or skill to digest complex problems and compare various solutions.
This party I'm working on, is, of course, dependent on GVTs existing (though the states with GVTs for their upper houses is plan B).
But I also really believe that without allowing new, interesting, breakthrough ideas to bubble up we're at a loss. This is because it becomes harder to correct errors in the democratic process without GVTs. I've written in detail why here.
Hope this provides a unique and valuable perspective.
PS. if anyone is thinking 'right on' when they read this, please consider becoming a member of FLUX. We need to register as soon as possible if we're to stand a chance at contesting the next election. Have a read of the site, you can see my lecture in the understand for lots of details.