Why did Psylocke never get mainstream popular? On paper she's awesome, but rarely ever talked about outside of niches.
They fucked up her character a million times by changing her powers. Also, she was dead for years IIRC. Betsy was kind of a joke character in the beginning as the sister of Captain Britain, then she was a weird villain, then she was put in the body of Kwannon and made a badass ninja assassin telepath with psychic knives. At her coolest Psylocke was killed off. Brough back later because the x-men needed a new jean grey (cuz grey was dead), then they expanded the number of mutants and added a ton of other telepaths making her kind of redundant. At this point Psylocke sort of waffled around to different writers and her powers changed constantly.
These days Betsy isn't psylocke anymore now that she has her old body back. Psylocke is just Kwannon now.
Psylocke actually is a very popular character but in the modern day she is too problematic. Basically a hot Asian ninja who wears bodysuits and leotards is satanic in this day and age. I have been extremely surprised that her new comics (as Kwannon) have allow her to be in the leotard.
Her look is certainly iconic.
She is an rather popular Cosplay, and while many wont know her name they will recognize the outfit (purple/blue with red sash). Olivia Munn actually did an okay job portraying Psylocke (physically) in that terrible movie, and the movie outfit was close enough for people to relate the two characters. Psylocke just exists in this weird character limbo where people are like, damn she is cool as fuck, why isn't she more important? Sorta like you did
.
Laura Kinney (X23) exists in this same limbo because marvel doesn't know what to do with her. She is was originally written as a darker, more ruthless, version of wolverine, then they ruined her by trying to turn her into wolverine and taking away the lethal edge she had.
TLDR: Marvel has no idea what to do with dark female characters that aren't villians because their default treatment of female characters is to either give them "YEAH, GIRL POWER!" or make them damsels in distress.
Just look at how they butchered Emma Frost...