Yes and no. Sampras was also totally slamless the year he took the #1 spot from the first time. And he took it from Courier who was holding two slams. And yet he didn't get a thousandth of the flak Wozniaki got, because he had won a (single) slam to and a half years before. Makes a world of difference, actually.
For getting to #1, winning slams is actually a huge *help* (2,000 points each, people). Getting them without winning slams is actually doing it the hard way (you need much better results overall). And as long as you don't have the "he/she never won a slam, so he/she's not fit to hold the #1 ever" stigma, then it's fair game. And let's be frank, Federer is about as far as you can be from that stigma.
That would be like Nadal not winning anything on clay and getting an award for best clay player, with trolls coming out of the woodwork to remind us that "oh, but only the YTD results count." That would be just as silly, imho.