I didn't like Ro at first but after a while I think she had added a lot to the series. If someone behind the series wasn't so dead-set against secondary characters it would've been nice to see her develop. (Or see her be on DS9 as a regular.)
The Powers That Be wanted her on DS9 as a regular - it was only because Michelle Forbes didn't want to do it that the retooled the premise and gave us Major Kira. I often wonder what a DS9 with Ro instead of Kira would have been like...