It really wasn't, and they had an apparently-non-binding statement that developers would be able to use old versions of the engine with old versions of the license perpetually. The new management abolished that good-faith statement and decided that, from this point forward, all versions of the engine use only the new license.
Where this is really going to hurt is games that have been out for a long time and are in their long tail. Even if you're selling for twenty bucks, but 100x as many people are reinstalling an old classic as are actually buying it new, you're losing money by keeping it on the market.