They host conferences around the world because attendees to the conferences in question are from around the world, and because ISOC wants to attract more of them.
I'm prepared to listen to real arguments about why ISOC sucks. But yours are either uninformed or you're not explaining them well enough. My bet is on the former. ISOC is not a charity, just a non-profit, and they've done quite well at keeping the IETF/IRTF and related groups going for decades.
Another thing you need to understand is that most SDOs (standards developing organizations) are pay-to-play. ANSI, OASIS, IEEE, Unicode Consortium, ... -- all pay-to-play. IETF? Free to participate. You don't even have to go to the meetings. Sure, participation == time == money, but being so accessible is a wonderful thing, and it takes an ISOC to keep it so.