Respecs tend to only appear in games like RPGs where there is a good chance that early choices can cripple or harm a character's development. RPGs, in particular, often require an abundance of knowledge and system mastery at the beginning of the game (when your character is created) rather than the end. In fact, some of the choices you make at the beginning of an RPG when you have the least knowledge have the most impact on the game (class, race, stats, alignment, etc.). This is actually the opposite of how many games work today (e.g., introduce a mechanic, let the player explore that mechanic. Introduce another mechanic, let the player explore that new mechanic, etc.).
While I'm not suggesting that players have the ability to change their class or race, respecs help alleviate this issue by allowing players to effectively make new decisions after they've had time to actually know their ramifications. I know that respecs are not popular choice, especially among grognards. And there is definitely something to be said about permanency and consequence that helps put the "RP" in "RPG".
However, not everyone has the time to devote endless hours in restarting a character and exploring viable options in an already large game. The long path in developing a particular "build" can have the opposite effect that redneckdevil implied: when character choice is permanent, and a large amount of time is required for a build to mature, players will tend to go on the internet to find the best build and copy it rather than devote hours to exploring whether or not a particular build is viable. A good example of this is Diablo II, where most of the work (read: hours) was done by a select few, and copied by everyone else reading a forum.
Sawyer has explained that he would like everything to be "viable", but that doesn't necessarily mean that at higher difficulty levels that building a party of 18 CON characters with terrible skills is going to work, regardless of your playing ability.
I'm an RPG veteran. I completed the backer beta on Hard and played a bit on Path of the Damned. The beta is fairly short, but I quickly found some of my earlier choices and assumptions in this limited area to be wrong as far as what I was trying to achieve with a particular character. Why? Because I wasn't familiar with the system. After experience with the game, I quickly realized that I had made an incorrect choice, but I didn't have enough information at that time to recognize it.
I personally would support some kind of respec, but with an associated cost as to make it non-trivial. In this way, there is still some consequence in character choices without forcing a player to restart a game with a character they feel isn't built the way they really want. Of course, once the game ships, someone will inevitably create a trainer that will allow you to respec, but it's unfortunate that one will have to go to some dark corner of the internet to download a 3rd party EXE to do it (talk about breaking narrative).
Of course it's not a necessity that a player make all the "right" choices, but for some of us, that's one of the reasons we enjoy these types of games.