By design, some are really easy to get (I see you'resaw you were wearing Retro Fan, which is one of them); e.g. Team Player only requires you to visit a single page. Others are really hard to get, like Red Baron. There's even one I can't get at all. It's the same as with badges; you could say that there are 'bronze', 'silver' and 'golden' hats.
I'm sure somebody will pull some numbers about how many hats have been earned this year, after the end of Winter Bash. Example from Winter Bash 2016. Only then we'll know if it was really harder this year.
P.S. this question is on its way to earnhas earned you a secret Sun Wukong hat!