To be fair to Troi, I wouldn’t say she was the hottest woman, but among a full cast of older men, she was bound to stand out as one of the few regular women who were also young. and reasonably atractive. As opposed to, say, Pulaski, who was already on the older side, or Guinan, who’s charismatic because the writers gave her good lines, but Whoopi wasn’t known for her beauty even then.
Marina wasn’t a supermodel, but she was fairly attractive, like a girl-next-door type, and among a cast of serious adult men, she naturally stood out. And she easily stole many trekkie's hearts. She was lucky she didn’t have competition from a regular like, say, Jeri Ryan was for Kate Mulgrew. She was a big fish in a small pond.