I think this is one of those features that would be useful to more experienced users, but would cause a lot of confusion for newcomers. I imagine Ashley has forseen the onslaught of 'performance issues' and 'bug reports' that would inevitably arise from improper use of such a feature.
It's also quite possible that this would require some deep changes to the engine, given that, in its current state, textures are only unloaded at the end of a layout.
Still...I would like to see this. It would make expansive, single layout games possible in C2, even on mobiles. I see the recent addition of 'Reload Layout X/Y' as a sign that Ashley has some interest in facilitating this.