I love and hate Eclipse/STS, but I don't think I will ever switch to IDEA, I love my freedom more. The least I can do for open source community is to use open source products and report bugs.
The IDEA Ultimate edition also supports lots of "enterprisey" stuff that the CE doesn't. Lots, of stuff.
But in general: apart from the actual whacking out of html and css, "web development" is normally just software development. There is no difference in my need of autocomplete/intellisense/code navigation etc. when I do web things than when I do mobile/desktop/library or any other kind of development.
I'm fairly neutral in this. I love open source, and I do believe in many cases, open source can be a lot better than closed source options (look at Apache httpd, many web frameworks, git, etc), but there may also be instances where closed source results in better software, and those developers deserve to make a living too.
I love open source, but I don't mind paying for quality when it really is better than the free version.