Three of a kind is one of the strongest hands available in Five-Card Draw. There are a number of reasons for this and a number of benefits that arise from this. At core, though, three of a kind provides you with a strong hand that also has room to move and play the draw/re-draw game.
In draw poker, most of your information and the other players' information comes from observing the combination of draws and bets other players take and make. This is how we judge each others' strengths and plan our actions. Three of a kind allows you to make draws and re-draws while still holding on to a relatively powerful hand. Remember, though, that three of a kind isn't a killer hand. It's a solid hand, and it can win you pots, but none of this is meant to imply that three of a kind is the be all and end all to draw poker hands. That being said, more pots are won with decent hands than with great ones.
The strength of three of a kind is also based on the value of the cards. Three kings is a stronger hand than three sevens, but of course the difference in value between two hands of three of a kind only matters between those two hands. Against every other kind of hand, three of a kind is three of a kind.


