I saw an interesting post at Keen and Graev's about respecs. I somewhat agree with the idea that making it easy to switch roles at the touch of a button seems...unseemly somehow.
But then I had another thought. Suppose you had a game without talent trees or specializations. So all you had to do was swap armor to go from tank to DPS. Isn't this the same thing from the outside? You press one button (your armor swap key) and you switch roles, just like an easy respec.
Yet why does switching armor seem so much more acceptable than switching specs? The end result is the same. Should we make it hard to switch armor, so that you can't switch roles easily?