I think you need to be careful about what you infer from people's choices. If a game allows players to take short-cuts, everyone will choose to take them because why wouldn't you? But a game that doesn't allow players to take short-cuts may well be regarded as a more challenging game, and be more popular in the long run as a result.I don't think I'm making assumptions because every single learning by doing system with a skill sum cap I can think of gives people both options and they overwhelmingly pick pinning their skills over perpetual drift. I think there is no reason to assume that they would be happier if their preferred option was removed.
I don't, because it's not realistic. In the real world, there is no skill that is inaccessible to me simply because I have learned some other skill. And in the real world, there are no archetypes - everyone has a varied and unique skill set. Having said that, I like the idea of characters being more effective if they focus on a subset of the available skills than if they try to do everything, and the idea that some combinations of skills work together particularly badly because they benefit from diametrically-opposed character traits.I like it when characters have some significant abilities that are exclusive to others. Especially when it comes to archetypal stuff.