As the old saying goes: You have to draw a line somewhere.
Transport Tycoon is a transportation simulation game, not a civil engineering simulator.
If you want to build towns/cities, play Sim City. That is my personal oppinion. And frankly, Im too busy building railways et al to be building towns/cities.
Likewise, if you want to build transport networks, you dont play something like Sim City.
Plenty of people used to question why I played TT back in the days. They always used to say "why dont you just play Sim City". Clearly they did not get what TT was about, and IMO, Sim City isnt exactly challenging.
As custodians of the project, the developers have to try to reach a balance between those features which are truely advantageous to the game and those which are just "cool ideas". Sometimes it means leaving out ideas which in practice are good, and found useful by a large number of people, but dont fit with the over all strategy of the project.
Im sure you all knew that though.
And for what its worth, I dont believe that should be an issue forking OpenTTD into your own branch where you can add which ever patches you want. OpenTTD is released under the GNU license, and as such is available to anyone to modify as they please, as long as the modified source code is made available to everyone else to do as they please, etc etc. You just have to be motivated enough to maintain your own project though.