The problem with the "no respeccing = you have to think about your decisions" angle is that it puts a huge crimp in the developers' ability to fix/change/balance things down the road.

Because "thinking about your decisions" leads to choosing the most effective combination of skills/abilities/talents/whatever, which are, by definition, the ones most likely to be made LESS effective if the developers are actually allowed to work on balance.. so what are you supposed to do? Go flavour-of-the-month and then reroll every patch, like in Diablo 2? Go for middle-of-the-road stuff in the hope that it is effective enough now, and not likely to be nerfed in the future?