She has a line after you recruit her that because of the mind control and powerlessness she isn't in a place to resume the romance, she mentions a maybe later to give you hope, but I mostly read that as a "we can be friends but I've got stuff going on" which as you get more of her backstory in dialogue, especially once arriving at the city and fighting her ex-, yeah she''s going through some stuff that'd make her not want to be romantic?
I massively support giving her more content, but I'm not sure lack of sex=lack of content. She's one of the most interesting companions in the game through her interjections and dialogue, what she lacks in companion quests and goals more than anything else.
Having her recruit-able in both resolutions of Act 1 would incentive giving her more content, quests and dialogue, and even romance stuff

Minthara is the best character and she NEEDS to be recruitable if you side with the grove!
Also- I support the important thread in the suggestions: Let everyone in the Party Speak