Popularity polls are not so bad since they are about character, but it is even worse to consider how shonen jump bases everything in polls.
If a serie is not voted enough in polls, it will get axed. Now what's the issue? Is a series appeals to a more mature public, they will most likely not bother to vote for the series they like compared to kids who find sending their votes to a magazine like something new and enjoyable.
A lot of times when you compare online polls with classic magazine polls you see how the results are TOTALLY DIFFERENT, since little kids are not so good with computers but teenagers and young adults don't mind so much voting using hashtags in twitter or by online polls.
I'm sure a lot of series with great potential, like Mx0, wouldn't have got axed if online popularity was a thing back then. But the ecchi is bad for getting votes (kids won't tell their parents they want to vote to the ecchi series), same for things were kinds cannot self-insert or be edgy.