I remember reading that at the start of the fourth season, the cast was asked if there was anything they would like changed or modified. Nana Visitor mentioned she wanted a uniform that allowed for more movement. Thus, a new, sleeker uniform was created for her. It is odd that no other Bajorans wore anything similar, but the redesigned uniform was so close to the originals that it never really bothered me. Plus, its in-keeping with the conventions of the Star Trek univerise. The beautiful female lead always gets to wear whatever she wants - as long as its form fitting and/or revealing!
Even though Kira's uniform was tight, and Nana Visitor looked fantastic, I never felt she was played as the show's sex symbol. Even Jadzia, who was very open with her sexuality, was not truly made up to be the sex symbol. They were certainly very attractive women, but they didn't have to show their cleavage on a regular basis (Troi) or wear extremely form fitting catsuits (Seven). They were very respectable characters.
As for Kira beating people up, I always wondered if she would actually be able to fight as well as she did. I'm sure she was a physically strong woman and saw her share of fights in the resistance. Perhaps she beat up plenty Cardassians twice her size in her day, so taking on Damar or Rosot was second nature to her? It may not have been plausable, but it sure was pleasurable to watch Kira kick some butt!
-Aaron