Yes. Having two amazingly hot straight women play-act with a few smooches is actually regressive.
The sexuality of the actors is irrelevant. The better actor should get the job. Plenty of queer actors play straight, and more recently a number of straight actors have played queer. So this is not a matter of unfair discrimination or lack of representation. Straight actors are not taking queer actors' jobs ("Build the wall!"

Anyway, I agree that "relationships" have generally been done pretty badly in Trek, but I'd say Julian in DS9 was an exception. His modest attempts at womanising and his pining for Jadzia were part of his character.