Micros are more for people who haven't quite got the experience to go pro. Sure, not everybody wants to go pro, but those are the people who I think micros suit. I'd say that $1/2 is when limits start being professional - I'm sure that with many tables (and possibly in countries where it's cheaper to live) that lower stakes can be just a profitable - but I'd say that, given a win rate of 10BB/100 (just over an hour, usually), that's $20/100 at $1/2, which is a decent salary. If you enjoy micros, stick to them - however I'd seriously suggest playing just one or two levels higher if you want to take things seriously. There are a lot of fishy players in 1/2c that could easily cost you quite a bit of money at times, whereas in 2/5c or 5/10c, players tend to be much stronger (and therefore better to play against) for not much more of an investment.