Sam,
iFixit is great for people that want to repair their device themselves. iCracked offers an avenue for the other 90% of people that need their device fixed but have no desire to do it themselves. Think changing your oil yourself or dropping it off at Jiffy Lube. I imagine Jiffy Lube makes a lot of boring money as well.
We have some really cool ideas in the pipeline that will be released over the next few months. iPhone repair is just the beginning, not the end.
-AJ Forsythe