The guy was flat-out good, no question about it. Had the Dodgers gotten him 5 years earlier, though, imagine how much of the 1940s they could have dominated.
Jackie Robinson did a lot for baseball to break the color barrier. For one thing, he was good. He had to be good, after all; the Dodgers would take quite a risk in putting him on the team, including trading some racist players who couldn't handle playing alongside him. To be good, he would need not only his normal talent, but he couldn't be phased by anything that would come up, including taunts from opposing teams' fans, players, etc, and that's to say the very least. Duke Snider notes that Robinson was a very tough figure, and that mental toughness was necessary to make the transition to playing in the majors, particularly as the first black player in MLB.
Another thing that should not be forgotten is how good a player he was. Robinson was one of the premier players at second base not only in his day, but all-time. Robinson had the 6th highest OBP of second baseman in MLB all time, behind only:
Rogers Hornsby,
Eddie Collins,
Max Bishop,
Cupid Childs,
Eddie Stanky
and of those players, only Hornsby had a higher career slugging percentage.
As far as defense goes, Robinson played his most games at second base and third base, putting up a Rate2 of 110 and 116 at those positions, respectively (compare to Hornsby's career mark of 99 at 2nd; note that Rate2 is such that 100 is considered average at the position).
But that aside, Robinson was a bold man and a leader, and he is an inspiration to anyone who wants to overcome prejudices to succeed. There have been great players that play the game, but not in the same circumstances, so it is only natural that there is no Babe Ruth day, etc. Robinson's contribution is so unique, MLB is right to honor him in such a way.
