I think the decision to limit the specializations is great personally, a vocal minority are broadcasting lots of hate about this decision but as far as I'm concerned it's great for the following reasons;
1) Forcing the player to make a decision adds another strategic choice to the game, always good in a strategy game.
2) It is great for modders as it enriches the possibilities for custom tech trees.
3) It can be modded out by editing the tech trees to make the current specializations normal techs instead, and no doubt someone who doesn't like this decision will quickly make such a mod available, pleasing those that don't like this.
One of the main objections I've heard is that this reduces the amount of tech there is to research, and they don't feel there are enough, to that I say the answer is to add more techs as they no doubt will with the spying expansion and others. Modders can also extend the tech trees if they want to.
So yes I think this was a great decision.