Instead of Credits, Craft Needed Era Materials

How about, if we start all over again between the three Coliseum PVE Opponents, even after constantly upgrading the marquee character, let us craft/upgrade lower level Era materials gained as rewards to relevant/needed Upgrade level Era materials for the current Era we are in (marquee character)? I mean, this supports both F2P and Spenders Alike.

This would be much like Relic upgrades,  it could use the phase 1 Era Materials I don't even need or see anymore as my STL is on level 36-45 Materials, you need to combine x mats into x mats etc.

Credits are cool and all, but the only way you can get them is when the individual (1 of 3 PVE Opponents) restarts, and you have to start all over at LVL 1 Opponent. At the end of that Era, sure, cash out remaining mats to credits (at least that's the way I understand it).