Poker is about the decisons, not the results- you know this.

If you bet a dollar against another guy's dollar, your odds of winning the two-dollar pot determine your probable profit or loss. (probable gain is synonymous with eventual "expected" gain over time; over time probability asserts itself more n more.) Flip a coin twice, you might get 100% tails, nowhere near the probable / expected outcome of 50%. Flip a coin 10,000 times, you're going to get much closer to 50%. Flip it a billion gazillion ++ etc. times heads will seem to come up exactly 50% of the time.

So if you have 60% chance to win a one dollar v. one dollar bet (2:1 odds), probability says you will win ( (.60 * $1) - (.40 * $1)) = $.20 or twenty cents. Sometimes you will lose a dollar on that bet. Other times you will win one. Probability says that you'll win just enough more that basically you're "earning" 20 cents on that bet.

Basically, whenever you're ahead and you bet, you "earn" money. (+EV). When you're priced right for a draw and you call, you earn money. Basically, right moves = +EV = $$$$$.
Yes this shlt is redundant to a great many players on this board, and doesn't even cover the half of it. However, its a basic explanation.

When you have the nuts, and you know the villain is willing to die with his hand, then betting more, or the most (allin) increases / maximizes how much you earn. I think that it may be +EV if you can wait to see if the draw hits or not (minimize loses) only if they will still call allin if it does not (which you are saying). However, you'd have to be pretty damn sure the guy would die with his hand, even after the next card (if his draw doesn't hit, or a scare card comes and he gives up)- also, you'd have to be disciplined enough to fold when his card comes (fold your straight to a **possible** boat).

IMHO, you'd hafta have a helluva read and incredible foresight to squeeze out the extra +EV on this hand. I think most times it'd be better to push with the nuts if villain will call surely.