Modding is simply a concession that the designers don't want to put up with any more crap or complaining and are basically telling you to "do it yourself".
^ This is what is wrong with the entire gaming market.
Modding has always been like that even for C&C games. It wasn't Westwood who made XCC, FinalSun and all the similar tools, though EA did make the map editor for most SAGE engine games and a mod SDK for C&C3 and RA3.
There are companies today that more or less embraces modding like Bohemia Interactive, Mojang, Eugen Systems, Valve + a bunch of indie developers.