If I have to hypothetically go through a bunch of dagger perks in sneak, to get to the bow perks and I dont even use the dagger, that will be lame and pointless.
Well, a typical "tree" would be more like..... to get Awesome Tier 3 Dagger Perk, you need Average Tier 2 Dagger Perk, and So-so Tier 1 Dagger Perk. Crap, I hate the Tier 1 Dagger Perk..... but to get the Tier 3, I have to take it.
But, like I said, this is just a general behavior of "Tree" style talent systems that I've seen in other games. We don't know if Skyrim perks are tree, tier, hybrid, something else..... but that doesn't change the fact that in many perk/talent/etc systems I've seen, there's at least some amount of "have to take this svcky thing in order to get awesome thing".
Like... I'm playing Roland in Borderlands right now. In order to get the tier 2 "increased ammo capacity" talent, I need to have spent 5 points in the Tier 1 abilities above it. Which are "increased HP" and "your turret does a slow heal-over-time". I'm not thrilled to blow 5 points in either of those, but I have to in order to get to the more powerful abilities further down that talent track.
Similar things show up in the talent trees in WoW. And in other games.
In Fallout 3, the drawback was that the more powerful stuff only unlocked at high character level, at high skill levels, or both. So you would only have a few perk choices left to pick them with. (Until they screwed everything up by giving 10 more levels with Broken Steel, of course.)
Yeah, sometimes it's bad game design. But alot of other times it's game
balance.
edit: of course, Borderlands or WoW-style talent trees have no issue with saving points til later, since the condition for choosing higher power talents is based entirely on your other picks, not on level / skill level / story completion.