[iamastud]

Letting more people stay in past 3rd allows for the paired doorcard to happen more often in the hand. As far as getting away from the hand when someone pairs doorcard, it should always be easy to get away from such a hand, whether it was raised or not.

Now by raising, you at least know that the people have something when they call your raise and thus if they pair the door card you kno that their are good chances that he has trips or 2 pair, but if it is an unraised pot on 3rd, you do not have this information on 4th should the situation arise.

But also, the reason to raise is not just to get people out but also to get more money into the pot when you believe that you have the best hand.