The bike was simply a gameplay gimmick in my opinion, and a quite troublesome and unnecessary one at that. As some of the community have pointed out, what would happen if you decided to just leave the bike there in the middle of the street? It's not like in
Pokémon where the bike can seemingly be stored in your pocket or something. With the amount of people walking through Dobuita at any one time, navigating through the streets with the bike mightn't have been the smoothest ride (no pun intended) either. If NPCs getting in the way posed a problem for smooth navigation with the bike, surely just some of the solutions would be to either reduce the number of them on the street at any one time, to have them move out of the way long before reaching them, or to do something to the collision so that getting really close to them 'pushes' them to the side. Just sounds like more problems than benefits.
What about when you unlock the ability to go to the harbour: would Ryo ride the bike all the way there (with a black screen transition in-between) or would he say, "I should leave this here," before dismounting the moment he touches the boundary between Dobuita street and the road? If it's the latter, would he really just leave the bike there in the middle of the street like that?
I have to admit, it would probably work quite well for navigating the harbour, but even so, would it really make all that much of a difference compared to running, especially when running offers so much more control and roughly the same top speed over a bike?
Nothing against those who are working hard to mod the bike back into the game - I seriously admire your dedication and love for the game - but it's something I could never see myself using if it were left in the game. Everyone loves a good run through Dobuita