Things to tell your roommate:
There are some holes where IC2 was, but only a few and not very big ones.
Marble and Basalt have been replaced by White and Black stone from MineFactory Reloaded. Both colors come in much more varieties than Redpower's did.
Tekkit Lite was somewhat bloated, and while Tekkit is a little slimmer there is so much more to do. You couldn't go to the moon or build your own space station in Tekkit Lite.
Part of the challenge of the new Tekkit is learning to do the same things in new ways. For example, you can't craft a jetpack, but you can add one to your very own custom PowerSuit.
The new Tekkit does not rely on Mods that are no longer updating. Eloraam has far to much real life stuff going on to maintain RedPower, and Abalaka is burnt out and is no longer developing IC2.