Not that I think going straight to the source will sway you, but…

Brannon Braga:

It was late, but I was so excited […] He [Rick Berman] really liked the idea but he had the stroke of genius, ‘Make it a Borg babe.’

Jeri Ryan:

I knew exactly what I was in for when I had my first costume fitting. Clearly my character was added to the show for sex appeal, which remains the one way to get attention very quickly. I don’t think it’s the only way to get viewers to watch strong women, but it worked.

So no, “spandex are very scifi” doesn’t hold a lot of water in this case.