[cpk]

Position (both relative and absolute) modifies the value of a hand significantly. A hand that would definitely be profitable on the button is not profitable up front for that reason.

The source of this difference has been covered fairly well by other posters. The main problem you have is that you don't know how much it will cost you to see the flop. These two hands depend on implied odds for profitability. If you get raised preflop your implied odds diminish. The chance you will face a raise is much higher from up front than it is on the button (or, alternatively, on the button you already know that it costs too much and can safely fold).

Even if you get lucky and survive to the flop, you are still out of position. I forget the quantification of this disadvantage, but its a lot higher than most people think.

Someone mentioned open-raising with a hand like this for variety in a tight game. Even this is dubious, though, because 2 bets is just too much for either of these hands unless you get a lot of help (and T9s is helped a lot more than QT). Further, you will often get reraised, and now you are out of position, investing too much money into a pot that is now large enough to require further aggressive action.

When can you put yourself in this situation? When you play so much better than your opponents after the flop that you can overcome this severe disadvantage. Don't kid yourself, though--very few people play well enough to profitably do this. No, in tight games you are far better off with isolation raises in late position with marginal hands and blind steals--at least then you have the benefit of position and are not as likely to be reraised by someone behind you.

Conclusion: Marginal hands are marginal for a reason, and bad position makes most of them unprofitable.