Whilst I'm not good enough to solve cryptics without using a thesaurus/wikipedia, +occasional google for today's obscure ones, I don't think that's what they are about (at least for semi-noobs like me).
It's about looking up obscure stuff in wikipedia that you'd never have looked up before (e.g. lots of artists/authors/etc.) for me.
I only resort to a missing letters/anagram solver if I am desperate though, and I hate when typing in parts of the clue gives the top result from DanWord which gives you the answer with no explanation, I hate that, try and close my eyes and scroll down as fast as possible then!