3 Pikmin IS kinda dumb...it just seems ridiculous that the guy who needs 100 pikmin to kill a mutant ladybug is going to be fighting the king of evil and other powerful fighters with 1/33rd of that. Plus three pikmin only is just aesthetically tragic.
Back to Canon versus non canon arguments, change versus conservation.
I have faith Olimar is going to be well balanced and serve the fans well, this seems to be shown in every character we have seen. It makes him a bit easier to use to only have three Pikmin sure, but it also makes the entire screen easier to watch, making it more based on skill and less on chaos, which is again, a competitive edge, and I think had as much to do with the Pikmin number change as the graphics limitation (evenif 24 pikmin could be on the 3ds stage, I would not want it, that would be cluttered and confusing each time Olimar were chosen, and it would ruin the character for me). It forces players to use them wisely and effectively, and not button mash.
Three pikmin at a time still keeps his essence, and allows him more strength in giving each Pikmin more responsibility, less time needed to draw them (because in my understanding, the balancing of his attacks would mean each Pikmin must be stronger if there are fewer, or each attack is just weaker overall which is implausible), and, of course, helps his other aided attributes, such as a new recovery.