Well, I never really had problems with my /focus macros.. the first macro I hit is the /follow macro anyway.. so why not implementing the /focus <mainname> there?
But about the auto-targeting thing: it's an internal WoW script that makes your toons automatically target the mob, that attacks that toon first..
and there's no way to turn that off! Just got with either the 'party1' or the 'focustarget' macro... I don't see why one shouldn't use those,
but every macro has its flaws...