How many times have you bought a game played it for a couple of hours and then dropped it because the doesn't catch you just right and how many times are those games over the £20 mark. Quite a bit I'm sure and why should I have to pay so much for a game that doesn't live up to the hype. What I would love to see is a company that allows micro payments for games I think that the STEAM system would be great for this. So lets take the Call of Duty series of games as a starting point. I've owned quite a few versions of this game except for Modern Warfare 2 (I objected to removal of dedicated servers) so no money from me for that game.
So I've bought and played Call of Duty 3, Modern Warfare, World at War & now Black Ops. If I was producing a micropayment system I would make it bill the user for every hour of play lets say 50p and here is the crux up to a total bill of £30. Lets say you download and install for free the new "Black Ops" game then you start playing once you have played 60 hours you will have paid for the game with out any problem, now if you didn't like the game or any reason and only played 3-4 hours then your only billed £2. Of course if new patch comes out that fixes a load of problems then you are more than likely to come back and play the game again or at least try it out and get billed another couple of quid.
Basically you will play the games that interest you and that you play if the game developers make a game that entertains you, then you will play it and feel comfortable in paying full market price for the game. An example of why this would benefit the consumer is the "Quake Wars Enemy Territory" game definitely not worth the money in my opinion but as a PC Gamer I can't return the game to the store for a refund as you'll be told "its already been installed".
For instance I played "Modern Warfare" for at least 2 hours every day for 2 years that's 700 hours. If companies were willing to do this then they could add in game purchasing for expansion packs.
This would also work for other software not just games.