I love tile laying games (Carcassonne for example) because of the re-playability, so that is a point for it. I really like how well Firefly integrated cards into a board game, so that's a point for it potentially. I like having games with a cooperative aspect, especially if it can be ignored if you want (we have one or two people who aren't as big of fans of 'beating the players'). Honestly I would almost expect to pay less for the game retail, however if it doesn't catch on (even after a successful Kickstarter) you'll never see it in retail. There are a number of games that that is why I decided to bid on them... you never know if they'll make it to retail.
For example, there is a game called "Length & Wit" that I'm in for $35 (early bird). It's a simple word game that you know 100% what you're getting. If you're a fan of Scrabble, or the Words With Friends app, you'll probably like it. Probably even more imo. It's very portable, so a great potential travel game (you could even play it on the airplane if you had something to roll the dice in). I'm not so sure you'd pay $40 (the non-early bird base game cost) in retail. If they keep the quality materials they are using now it probably would (maybe even more), but will the materials, if it made it to the big leagues, suffer for better production costs? If they did would is cost less as a result? The #1 reason I bid on it is you may never see it elsewhere and, even if it were cheaper, it may not be of the same quality level.
Mostly I pledge on games or game related stuff, but I've actually put in on a flashlight and a ring. I've got a far lower threshold for what I'll pay on those kinds of things though. A few things I just throw in $1-$5 pretty much as moral/promotional support if I really like the product but don't need it or don't want to spend what it would take to get what I want. Like the Slaughterball game... I like the looks of it, the materials are nice, and it's a local company, but I'd have to spend close to $200 to get what I want and I'm not convinced it'd get a lot of use in my gaming circle. It's kinda like the casual gamers version of Blood Bowl - and my group would probably rather play Blood Bowl.