EEII was made by a different company.

The expansion to EEI was made by another company.

If you did something right the first time, it is hard to screw up on adding to it. CA demonstrates this, although I know you hate ETW, plenty of people think it is a great step forward. Aside from bugs, but that isn't related to gameplay.

Empire Earth wasn't similar to RoN.... It lacked most of RoNs ability to emulate the real world, as well as encouraging "classic" RTS behaviour. With RoN, mods made it impeccable, EE barely changed, since it was made to simply be an RTS.