I agree with the poster you quoted that without the switch Psylocke would be around Dazzler's popularity. And I do think Psylocke is more popular than Dazzler. She is more mainstream. No, she's not up there with the super A Listers and no she probably couldn't make a comic successful just by her mere presence. But she has been a mainstay of the main books for over 2 decades (3?). The same can't be said for Dazzler. So yeah, I would say she's more popular than Dazzler. At least a grade above Dazzler.
That said, she owes a lot of her popularity, not only on her new body and costume, but because she was part of the early 90s Jim Lee X-Men. Almost all the members of the Blue and Gold teams of that era got a boost in popularity (or retained their former prominence). To many, that roster is still seen as the definitive image of who the X-Men are and Pslocke was a part of that. Those that didn't make the cut, in general, got a downgrade. Some were able to breakthrough afterwards, of course. Kitty, Emma, Illiyana for example.
But I also think that Jim Lee would never have used Psylocke without her ninja form. So it kind of all goes back to her body switch.