I don't know about making Troi a regular, but I do think (as others - possibly you, RandyS, and perhaps maybe even me- mentioned way back when early in the thread), a visit or a few visits would have been nice so as to actually conclude the Troi-Worf romance rather than merely having it vanish without a trace and with no explanation or anything.
It was simply careless to chop off a relationship between two such important characters that way after such a long build up. I'm happy with the cast we ended up with on DS9, and I wouldn't really want Troi to replace any of them. (And I agree Siritis had her limitations as an actor, though she had improved a lot by the end of TNG.) But...it's just not right to have a relationship with so much build up that then disappears as though it had never happened. That's just sloppy. Common, sure, but still sloppy.
I can strongly recommend Peter David's Triangle, set in the gap between Generations and "The Way Of The Warrior".
It tackles the Troi/Worf relationship head-on--and as PAD himself noted, it helps explain exactly why Worf has the "whatever...I'm going to resign, anyway" attitude he displays in most of "Warrior".
It's a dang good book, too. But then...85-90% of PAD's Trek work tends to be dang good.
I'm not convinced it was her fault as an actress, per se...simply that she's only as good as the scripts she's given. And the stuff she was given, counselor-wise, tended not to be that great....(And I agree Siritis had her limitations as an actor, though she had improved a lot by the end of TNG.)