Time4Tea: This is very sad news. These are all classic games that deserve to be on GOG.
EA sadly seem to be living up to their reputation of caring very little for their customer base or the preservation of their older games. I think I'm done buying from them at this point. (Not that it will make much difference, since I'm not even vaguely interested in any of their recent games)
I'll guess a few things here.
01. EA wants to remake or remaster these. Why not? I'd guess ME:LE sold extremely well and C&C: Remastered Collection was well-received - so it's probably off to the races w/ more remakes and/or remasters.
02. Whether they do or don't on the above stuff (remaster or remake), they probably want to make them exclusive to their own service - so that all the profits for games sales go ONLY to them and also so it's a selling point of EA Pass subscription service.
03. As others and Stinging have suggested - maybe they sold the IP off to someone. Hopefully, if that is the case, it's in the hands of someone who actually cares about the game, franchises, and DRM-FREE.
This really isn't about what we, the customer & consumer, want unfortunately. Personally, I like options - I want my games on as many digital game-stores and platforms as possible. This way, the consumer can go for the best price, best package, favorite store/client-app, or grab a DRM-FREE version from GOG.
But, this is all about money and business to suits - and they're going to make a decision that helps out their bottom line most importantly to them, unfortunately.
EDIT - Good thing I bought these soon-to-be-delisted games a while ago, all from GOG.