How do you know that N64's 2D was "pretty much unlimited when compared to the PS1 or even the Saturn"?
Is it just because the N64 is cart based? The Saturn also has a cart slot and could have been the greatest 2D cart based game system of all time.
Well the biggest limitation with the PS and Saturn (the actual greatest 2D system of all time) was the combination of games on CDROM and very little RAM. The 4MB *greatly* alleviated this problem so its not a crazy thing to assume that if games were released on giant carts then you could see stuff like Street Fighter III on Saturn or N64 with zero compromise. The Saturn never saw giant carts though, and the N64 never saw an epic 2D game.
Truthfully though the N64 had so few games with good 2D in them that its not %100 certain that it could have been a great platform for stuff like Princess Crown, SFIII, or Super Robot Wars Alpha even if there wasn't a secret Nintendo/Freemason policy against it. The best example of high grade 2D on N64 I can think of isn't Yuke Yuke Troublemakers (which is barely SNES grade most of the time) but rather the main character in Wonder Project J2. When I got J2 and saw how well animated the main character was, I at once began thinking that the N64 could be a great system for 2D fighters because the huge cart sizes would easily accommodate the CPS2/MVS norms. In the end a decent fighting game was never released for the N64 (KI wouldn't have solved this, btw, KI is pretty much Boost Mobile the video game, and sucks) so we'll never know for sure until someone makes a Neo Geo emulator for N64.
As for this B-Man game, I actually do remember it being announced and knowing it was real 2D, but sold my N64 years before and never looked back so I didn't get a chance to pay 7800 yen or whatever just to get another in a long line of B-Man games that isn't as good as '94 or SS.