There are lots of things impossible in the game, including having a flat world (unless you start with one, which is easy enough). Not only transmitters are in the way, but also villages and industries, for example. Todays AIs don't do much terraforming anymore, but the original AI used to reshape the terrain quite regularly.
resources are removable. if i don't transport any cargo for them, their production will decrease and finally close.
industries are the same. they will close by themselves.
villages are impossible to remove, but they don't impact to my railway network, since they are far away from resources and factories. a mountainous city is actually beautiful and i like it very much.
but transmitters, i can do nothing with them.
the purpose to make a flat world is to make a beautiful and efficient railway network. Transmitters prevent me to do so. Many many times.
i don't think transmitters give this game more factor of pleasure. maybe someone does, but why not let players to decide? a switch is pretty simple to implement, is that right?