Why are the two things contradictory?
If you don't even wear a fancy dress to a wedding, the fanciest event most people will attend, when do you dress up?
Fancier than every day dress doesn't automatically mean you'll never wear it again! It's not a binary choice between full on ballgown and something you can wear to the pub/work - which to me is what the new look dress is.
You can wear a "fancy" dress to another wedding, to a special meal, graduation ceremony, award ceremony, work Christmas party - or you can resell it so someone else can wear your fancy dress once and you get some money back.
Obviously it's different if you can't afford a special dress in the first place but to me it's quite sad to never be able to justify buying something a tiny bit out of the ordinary solely because you can't guarantee you'll wear it ten times!