When arguing semantics about the poll :
Please remember the wording of the question is less than optimal : I think (but I may be wrong) the real issue is "should Planescape lore be allowed anywhere near the core".
Please consider the results in perspective of Wandering Monsters polls : consensual issues are above 80% of 4 and 5 (from my own survey and estimate, not from any wotc staff). 56 % is "very controversial" at best for this big tent edition.
I still think Planescape is too rich a setting, too weird a baseline, adds too many overarching plots to figure in the core, which is everybody most basic set of tools.
Out of the core box, the game has to support the most fundamental tropes of fantasy : basically, either FR witj names filed off or 4e implied setting. I would prefer the latter but I am perfectly aware the former is the smartest move considering the fanbase.
Of course, that doesn't mean PS lore should be casually obliterated ! It doesn't mean, either, that 4e is innocent of the capital sin of obliterating previous stuff. But, now it's done, 4e fluff should be judged on its own merits, rather than having to atone again and again.