As much as I like and respect you guys, I'm going to take exception with pretty much everything you've said ...
IMHO, Cal Ripken's streak and Robinson's rookie year, noteworthy and significant accomplishments to be sure, were NOT "moments" at all. Even Aaron's 715th was not so much a "moment" as a foregone conclusion, the culmination of a long chain of smaller moments.
To me, memorable moments are the unanticipated, the dramatic change in direction, the surprising, ... I think Lou Gehrig's speech was a moment ... May's catch in '54 and Don Larson's perfecto in '56 were "moments" ... Gibson's homer off the Eck, now THOSE were "moments" ... and how 'bout the ball between Billy Buck's legs?? THAT was a memorable moment! ... even the line drive off Gil McDougal's bat that hit Herb Score in face ('57) was a memorable "moment", albeit a rather disturbing one.
I think that the problem is those doing the voting ... for the most part, they never saw a ballgame before the 80's, so "moments" are either recent events or are "feel-good" and "PC" occurances they've seen in old news footage ...
All that said, I thought the most moving of the "moments" we saw last night was Pete Rose ... I was pleased that he got a standing "O", pleased that he was included among the "moments" acknowledged last night and wish someone with a clue could take control of the process that would allow Pete being elected to the HoF ... it's off-topic to say so, but I feel strongly that he rightfully belongs there.
I'd have voted for Bobby Thompson's '51 homer being MY most memorable moment, followed by Gehrig's speech (even though I've only seen the film), Gibson's homer, and May's catch in '54, Henderson's homer for the Red Sox in their win over the Angels in the '86 ALCS ...