I didn't mean to be talking about being specialised vs being a jack of all trades. I was talking more about being able to focus on unusual combinations of skills; combinations which we can't easily classify with the traditional class labels. TES hasn't restricted you to the traditional stereotypes of warrior, mage, thief (and a handful of hybrid classes). It's whatever skills you like.
For example, a warrior might specialise in four or five skills---a weapon skill, an armour skill, block, smithing, maybe one more. But now consider someone who wants to focus on four or five skills, but it's an unusual combination like: One-Handed, Pickpocket, Alteration, Block, Alchemy. In a good sense, these two characters are equally specialised, because they're focusing on the same number of skills. But while the first character is a pretty traditional warrior, the second character is much more unusual.
But also, even if these unusual classes are not as "effective" as traditional classes, so what? Yes, you wouldn't seek medical advice/treatment from a part-time doctor/lawyer/musician. But the nice thing about TES is that you don't have to be the saviour of the world. You don't have to play the sort of character that everyone in the land is going to ask for help. You can play the journeyman mercenary. You can play the town's local scoundrel. You can play the anti-social hunter. That freedom has always been a major appeal of TES, I think.
FWIW, I think all of the previous TES games did this: in Oblivion + Morrowind because you could make your "custom class", and in Skyrim because you improved in as many skills as you used. So I just hope that this sort of approach doesn't change.