It's not that hard to create a "top 10 list" in plain text.
Seems you still haven't realized the feature is more than a personal one. Not all uses of the Top 10 lists would work in plain text when applied to the scope of the entire community. A bulleted (numbered, etc) list is fine if you want to list your favorites, etc; the idea fails at a larger scale when you want a community's opinion (a text blog list would also fail to garner the same input as a poll feature).
The poll tag feature has limitations and the other two proposed poll tags rely on external sites with questionable maintenance issues. As DaNASCAT mentioned above, Discussions may take on this functionality, and if it does, great. I wouldn't, however, dismiss the benefits that the Top 10 lists had by equating them to simple plain text.