[WesleyC]

GrahamJson, on 2016-December-25, 14:31, said:

I must be getting old, but I can't see how a hand that is not worth opening at the one level can somehow be later worth forcing partner to bid at three level.

I think the idea that you're missing is that a hand doesn't have a fixed value. During the bidding you need to constantly be reevaluating your side's potential as new information comes to light.

When LHO advertises a weakish hand with soft values in diamonds (your singleton) that hugely increases the offensive value of your hand.
Your singleton diamond also inferentially improves your side's defensive prospects because any diamond honours are in partner's hand sitting over declarer.

So even if you knew the points were divided exactly 20/20 on this hand, your side would still have a significant positive total point expectation.