classes in a skills-based world?

While reading the latest blog meme, which includes discussion of classes vs skills based character development, I had this passing thought... instead of all players being able to improve whichever skills they want, how about providing in-game trainer NPCs which only offer a specific set of skills. Thus, Master Yoshi of Black Mountain might offer a bunch of stealthy combat skills, but eschews anything better than a hard leather cuirass. Meanwhile, Warlord Wagan can teach you everything you need to become a master of arms, capable of dominating close combat, defending others.

Classes, in other words.

Provide lots of different trainers with different skill sets, possibly even add new trainers as interesting hybrid builds evolve. Provide some bonus skills or skill points if you keep going back to the same trainer so as to discourage rampant skill shopping, but nonetheless still allow the player to pick and choose nearly any skill of all available. Have some skill trees only become unlocked from a given trainer if the player completes a difficult task or quest for that trainer. It will still be possible to build a completely custom hybrid character, but you'd need to put in a lot more work.

Would you play in a world like that?