I just mentioned this in one of the other threads, but I think breaking the fourth wall was a big problem. For me, the effect of Seven was like watching a regular Star Trek episode and then suddenly having this bimbo from a model magazine show up in the middle of the story. It was very frustrating. Plus B'Elanna Torres was a lot hotter.
I'm not sure I'd describe Seven as a "bimbo". Yes, she was showing off her stunning good looks a lot (and that's something I can't complain about), but I do think she had some good stories to balance the sex appeal. And there were characters from before VOY like Deanna Troi and Jadzia Dax that played up the sex angle, so she wasn't really that controversial.