It depends (is a phrase you'll hear a lot in
poker strategy) on which pairs you are talking about.
Of course mathematically a small pair, will win slightly more often if there was no more action after the pre-flop round. The trouble is, there almost always is, which makes it very hard for small pairs (22-55) to realise their
equity. Unless you hit your set, your going to be faced with over cards that are going to put your small pair under a lot of pressure and probably cause you to fold.
Conversely with KQ, you have much more chance to improve to the best hand. If you have a small pair, there are only 2 more cards you can hit to improve to a set, whereas with KQ, you have 6 cards to hit, which will likely give you the best hand, plus the increased chances of hitting straights or flushes (with KQs)
This is why when you study ranges small pairs are often missing, but KQ is in 100% of ranges.