RTF is a global modification that replaces all towns in the game.

Why create new objects if they won't be used on maps? Of course, they might be used in campaigns, but that's still a long way off.

In principle, we could create a script that allows players to replace objects at the start of the game, if they wish. Well, it's the same idea as with cities. )
In my humble opinion, this is better than changing them without the option to revert them.