This is the most popular complaint against the TT. Many threads, pro and con, but apparently they did a survey and decided that the next version of the site will be different. A staff member made an announcement months ago that while you may not necessarily gain any points for a correct answer if you take your time, no longer will you lose points. Will V3 ever be finished? Will this make the cut into the final version? Your guess is as good as mine. 
Should Tactics Trainer deduct points for slowness?
This is the most popular complaint against the TT.
I'm not complaining, I just wanted to know what other's opions were.
Check out the archives then. A good thread to start with might be "Does the TT encourage blitz thinking" or something like that.
http://www.chess.com/forum/search?keyword=tactics+trainer
It can be both ways. As long as all participants face the same rules, the rating is accurate. Probably chess.com don't want to implement different types of tactics trainer, so they've picked one where time matters. There are others available online for one who doesn't want time to be taken into account. Nevertheless one can play the positions here without caring about rating - if a position takes you 5 minutes to solve, why bother to guess a move in 30 seconds just to try to keep up with some number?
I was just wondering what everyone else's opinion was on this.
If you get the tactic correct but take 'too long' should you lose points or should you stay at the same rating?