There seems to be a bit of a fallacy running through your post.
I won't lie - it's awesome having a wonderful, stable, long-term relationship. But one of the things that's so awesome about it is the fact that I spent a fair chunk of time before that being single, or dating guys briefly who didn't work. But those early boyfriends and dates weren't wastes of time. It was (if you will) panning for gold. Seeing if there was anything there. Seeing if this relationship would be a good solid one. And...the first few weren't. They weren't bad people - we just weren't compatible enough. We made decent friends or OK fuck-buddies, but we weren't long-term relationship material for each other. But that's OK. We ended up being much-better fits for other people.
What you seem to be saying - and I hear similar complaints from others "new to the scene" - is that you want to bypass that. Go straight to the end. "Let's just jump to the part where I meet the guy I end up being perfect with." Well, sorry, there's no real shortcut there. There are things to make it easier, of course. You can go online and read up on a bunch of guys. You can join gay social groups so you have at least one thing in common (biking, the arts, what have you). But your happily-ever-after isn't walking around with a big blinking arrow over his head that reads "THIS IS THE ONE". You have to find out if a guy is right for you. And you do that by dating...and often those dates are casual, and often involve seeing if you two are sexually compatible as well. That doesn't mean you have to drop trou and throw your ass in the air every time you meet a guy. But that IS something you're eventually going to want to find out.
Point being - just because guys date casually, or break up after a few weeks or months, doesn't necessarily mean they don't take the whole thing seriously. They probably ARE hoping to find that guy they mesh perfectly with. The breaking-up just usually means they haven't found that guy yet.
Lex