The only way it makes sense to develop for a 7-year old console is if your only interest is to make money.
Which is why publishers and developers tend to focus on consoles. Money takes precedence over all else. The developers who do it primarily because of their passion for it are either modders or indies.
Anyway, I don't think RAGE is a bad game. I'm finding it fairly entertaining, though certainly not $60 worth of entertainment. Worth picking up for $30 when all these issues have been fixed. But yeah, you should always try before you buy, whether there's an official demo or not. It will save you a lot of grief.