Polls on most big sites have to be requested by a moderator as they are very easy to get wrong and have always been a subject for controversy.
If, as said by Det, you desperately want a poll to be made about a thread posted then pm a member of the team and ask or even post a request in the thread and if it seems reasonable then one will be made - like the cats and dogs thread for example. Saw that as a resonable thread to have a poll on but worded the question in such a way that the poll on the front page would make sense to a non-member.
The main problem is that polls appear in more than just the thread they appear in so have to be worded properly for the sites other uses.

end of day how hard is it to ask for one to be made rather than do it anyway.