A good underwire is a thing of beauty. They lift, shape, and support. I believe that there are, in fact, underwire sports bras.
A good underwire will make a gal look about 10lbs lighter, on account of the instant boob lift.
A good underwire lets the clothes hang just right.
I have not worn an underwire bra in months, on account of avoiding any potential overconstriction of my breast tissue. I miss underwires. The softcups just don't quite cut it on my 38H figure.
(I'm sort of hoping that a year or so from now, when I'm no longer nursing, I'll go back down to something reasonable, like a C. Then I shall buy pretty bras without having to mortgage the house.)