As others have mentioned, psc-package can be used so there is no "need" for Bower.

"Why the PureScript community uses Bower" explains why Bower was chosen: http://harry.garrood.me/blog/purescript-why-bower/

I don't understand why Bower is such a sticking point for people. It works perfectly fine for PureScript and (as the article explains) was the right tool for the job.