I don't think you completely understand the concept of that. A lot of successful Indie Games use this. It boosts sales. The games may have a set "Goal" if reached, they will add more content. I really would suggest you read more into development of XBLIG. Would you rather pay for a game upfront with all the content and the developer basically gets no money at all for sales. S/he is promoting their game, successfully. I feel you are unsupportive of indie games. Again, I think you are overreacting to "Oh I'll make it a complete game if it sells". Does it say that? No! This is like saying XBLA shouldn't have patches. This is also you saying Mojang shouldn't patch Minecraft and add more awesome features.
The thing is its not a concept of expanding the game.
Dead Pixel is doing that and on its own the game stands up. Kodu game lab did / does this and on its own the game stood up. To release a slap dash terrible game and then only offer to make it into a working game if it sells is disgusting practice. People should not be looking for a sales boost by offering to create a game if people buy it, a sales boost should be if X people buy it more will be added on top of an already existing game.
I think I have read up a fair amount on XBLIG development, true I'm not a complete expert on all the aspects but I have a basic working understanding of how the indie games system works by now and how gaming should work.
Would I rather pay more upfront ?
If paying it means the game works and doesn't have the chance of never being fixed then yes they should charge more rather than potentially ripping off people who buy the game by giving them a shoddy piece of rubbish then saying they'll only fix it if it sells X amount.
Methods like this aren't a means of promotion for a game as its extremely negative for early purchasers to see someone saying essentially "oh yeh you know all those things you'd think should be in the game, well I'm only going to add them if the game sells well"
have you seen what the game didn't have to begin with ?
No health items
No alternative weapons
No extra locations
No online scores.
indie games should add worth if it sells not offer that if it sells they will add the gameplay elements found in other such games. Heck the $1 zombie game these features as standard and that's not even one of the best indie games with zombies in it the other being Dead Pixel which stood on its own to begin with and the DLC stuff does add more to the game too it doesn't feel like the developer has done a capcom and gutted the game to be able to get more money out of it.while this game really does feel like its been gutted to try and get sales