The most important reason why they did not include the ability to reset talents is so that you would have to work within the constraints of the talent choices that you have chosen.
Even though you have to level skills before you can put talents into their respective trees, I'm sure for many players it'd be so easy to switch from a warrior to a rogue that the game would lose much of its replay value, and these players would actually become less interested in it as a result.
There are some problems with systems like this where there are no takey-backseys, but it's better than being able to indiscriminately switch talents at a whim. However, I think there should be the addition of "take back points," where you are permitted to take back maybe one talent every so many levels. That would prevent total respecing, but would help players take back that one useless perk they took at the beginning of the game when they didn't know better.
But the problem with that is that there is a max level. A good idea would be at a certain level like 50, you can rearrange your perks.
I can guarantee that one of the first mods will be a respec mod, if you're on PC. The respec mod was one of the first Dragon Age mods to come out (and still one of the most popular).
Personally, I like the idea that our choices have consequences.
Consequently, I'm playing on a PS3. I guess I'll just have to buy a PC version when/if a respec mod comes out. I just feel sorry for thousands-millions of Xbox/Ps3 Players like myself who probably face this problem as well.