That's completely contrary to what I've experienced. Only browsers that "need" a little extra JS/CSS are the old IE versions. Quotes indicate you don't necessarily need to enhance pages in those browsers at all these days.

If your experiences indicate otherwise, you are simply doing something wrong.

PS. jQuery is horrible. Every time you think you've figured out all of their undocumented quirks, they change the logic. It's famously inept in IE 6/7.