Not necessarily contesting your point, but making some clarifications:
From the moment Scrooge got his own book in the states, he outsold Mickey Mouse and Donald Duck and his book has ALWAYS had the highest readership and fanbase. With very few exceptions outside of the norm - for instance if something special happens - that has still remained true to this day. Scrooge is the odd duck of the classic Disney characters in that he was the only one that DIDN'T have any shorts, but was actually a pretty well known character who didn't TRULY blow up until Mickey's Christmas Carol in the 80's.
A lot of people also forget that back when Disney was still doing those little educational animations and such - Scrooge was also the highlight of "Uncle Scrooge and Money", his first animated cartoon where he explains the value of a dollar and all that jazz to the nephews. In fact, Disney printed in the comics at one point, old storyboards that existed of what were a few planned storyboards for a Scrooge classic style cartoon short or two that never made it off the ground simply because they didnt really know what to do with the character at that time.
However, that is just in the states mind you: Overseas, Scrooge was and still is depending on where you go, WILDLY popular and well known. Especially in certain areas of Europe where Disney Comics have outsold even Batman, Superman, and Spiderman in many places.
To base your argument that kids may not have known who Scrooge was totally is somewhat valid due to lack of shorts, but be careful of stretching that too far because he WAS known, just not quite as well as Mickey, Donald, or Goofy due to his venue.
SIDENOTE, TOTALLY OFF TOPIC: Wasn't Bonkers at some point supposed to have been Roger Rabbit, but was changed due to the copyright clusterfreak that RR has always been in (which I still am not fully sure how it works)? Like...Disney owns Toontown, but not specially RR except at certain intervals or a joint partnership with Touchstone or something?