I'm not sure they get priority over others (WCG decides this?) but obviously there are only so many WUs and when they are gone, they are gone, so yeh, might not get certain badges. Badges are nice, but in the end, any work contributed, badge or no badge, is satisfaction in itself. I'll "celebrate" badge milestones as they come, but not going to lose any sleep over them. When I see how some crunchers have over 10 years on one thing or another it's definitely impressive, but it might the WU of some guy on a PII that makes the difference!
Oh, you're absolutely right. It's really a matter of personal preference.
But if you think about it, people who choose UGM exclusively HAVE to get priority - right? Because what would happen otherwise? If they have just UGM checked, you can't send them work from other projects as long as there's UGM work, so by default, they get priority.
That's not a big deal if only a few people do that, but get enough people doing it and it reduces the pool of work available to the people who have more than just the UGM project selected.
And BTW, I've seen this firsthand. When I had UGM and MCM selected, I had far more MCM than UGM wu's. I don't remember the exact proportion but it was really lopsided. I was making almost no progress on a daily basis in terms of the number of UGM hours I was racking up. And it wasn't too hard to figure out why. So I had to follow everyone else who was basically gaming the system and switch to just UGM if I wanted to reach certain goals in a reasonable amount of time. I don't really like doing this, but sometimes you have to go with the flow.
However I do agree with your overall sentiment as I said before. It doesn't really matter what you crunch with or how many points you rack up. What matters is that you participate. It's just that for some of us, part of our motivation is to be bluntly honest, a bit OCD oriented - at least in my case. I have enough machines that have enough power that I can shoot for some decent badges so I don't want to miss out on them just because I was playing by the rules when everyone else wasn't.