Are you saying it is somehow immoral/less moral to not buy from sweatshops?

Yes! People in Bangladesh need money for development desperately. It would be better to just mail them checks, but if you aren't doing that then buying from their (crappy) factories is better than nothing. Even if you are mailing checks the extra that gets contributed from buying clothes made in Bangladesh helps.

It's certainly counterproductive to boycott them if you don't do anything else.

You're assuming that's the only option. What about every single one of us making sure we buy from companies that demand more from their suppliers? What about more innovation around social change and activism and less around things like sharing photos and building "free" websites that ride on the evil that is advertising?

I'm definitely open to hearing creative solutions, but if all you have to say is that sweatshops are bad, you're not really contributing. Lots of things are bad. What helps is working towards what would be better.