As is 99% of women on TV. Troi was to be attractive, but thankfully they didn't give her three boobs.
She was ordered to wear standard uniform in "Chain of Command", after which people realised that she could look professional and still attractive and curvy so they kept it. She was a Lieutenant Commander from the start, though was only referred to by rank in "Encounter at Farpoint" and then again in S7 "Lower Decks" (when she and Riker joked about promoting everyone onboard) and again in "Thine Own Self" when she passed the bridge officer's test (she may have been called 'commander' in "Disaster" though I can't recall).
Worf could totally pull it off.
In the 1987 series bible, then-Lieutenant Troi was described as:
An attractive and very witty Starfleet professional, she is the ship's Counsellor, a position of vital importance on space vessels of the 24th century; the success of a starship's mission depends as much on efficiently functioning human relationships as on the vessel's mechanisms and circuitry. Troi is a master of Human and Alien Psychology, also a Starfleet-trained bridge officer. Her mother was a Betazoid alien and she has inherited a form of telepathic ability which allows her to "feel" the emotions of others. [She then gets another couple pages worth of character detail, which includes the elevated rank, further on in the bible]
So in the beginning they had set her up as an important mission specialist, vital to the running of the ship, unfortunately the writers (especially in S1) had no clue what to do with her, and so she suffered from their short-sightedness, so she was relegated to being the one in the skimpy outfits. But when they did give her a good story line (such as "Face of the Enemy" or "Disaster") then she showed what she was capable of.
Unfortunately, the PTB at Trek seem to think that the straight male and gay female population won't realise a woman has boobs unless she's in something low-cut or skintight which is why we wound up with Seven and T'Pol, both of whom (like Troi) showed that were far better looking when in standard uniform than any of the other crap they had to wear. But that is the nature of the TV beast for you.