Well, like I said a few posts ago, England actually did a survey several years ago that actually proves that kids DON'T like clowns.
As far as I'm concerned, Ronald's like the only high profile clown that isn't a parody or a tedious "teh clowns are teh scary" horror show (Steven King's It ruined everything for the clowning industry, I bet). And the funny thing is, the only clowns I like are parodies or cartoon villains... Krusty, Binky, Buggy, and of course, the Clown Prince of Crime, The Joker... seriously, if the Joker were McD's spokesclown, more kids would go there. but then that would mean he'd have to go straight and not try to kill Batman violently...
I mean, McD's Ronald came out of the 1950's and Clown based TV shows... in fact, they basically wanted their own Bozo so they didn't have to pay the copyright owners for public appearances, which made the growing McD's chain packed with kids. So basically Ronald was created as a cheap ripoff of Bozo. Now, kid's TV shows don't have clowns in them (Jojo's Circus is long canceled). Except, again... the Joker.
Interestingly, in almost every single Batman Happy Meal, there was a Joker figure/car (exceptions being Batman Returns as he wasn't in that movie and Young Justice, but it's not so much a Batman cartoon as a cartoon with Batman in it). I think I got most of them except for the Joker Lego Batman figure (I got the helicopter, though).