Having to build everything from scratch actually sounds like fun. Since I'm a modder and usually spend most of my time making Weapon packs and generic weapons to fit my needs I rarely Build anything decent. I mean, if we have the update, why not have something to look forward to?
TGE doesn't necessarily make for good interiors and terrain. They are simply ugly and too low poly.
I hate to see so many favorable maps disappear, but there will be more opportunities.