Your comments reminded me of a few games that have in fact tried this sort of system. Wizards themselves tried to “fix” Magic with several different games. The one that immediately jumps to my mind is Duel Masters (relaunched in America in 2012 as Kaijudo).
Duel Masters used a system in which you could play any card as a resource, which could be tapped as in Magic, but one resource of a color would let you cast spells of that color (you didn’t need two separate green sources to cast two green cards as an example; you could use a green resource and a red resource, you just needed that one green resource to enable your green cards). While it is still popular in Japan (as far as I am aware), it’s now failed in America twice (Kaijudo was discontinued around 2014, can’t find the exact date).
These two games are not direct comparisons, however. Kaijudo in particular had several things working against it — it was entering an already saturated market; it was designed to be pretty simple, and was specifically targeted towards a younger audience, limiting some of its competitive appeal (which, while not strictly required, really helps give a game legs); and its marketing smacked of trying to compete with Yu-Gi-Oh!, a much more established card game. I’m also not entirely sure how the FFTCG resource system works; looking into it is on my to-do list for the day. I hope it does well (WotC could use competition in the physical card game space, imo), but this all is to say that this sort of resource system has been attempted in various forms before (I think the WoW TCG — the ancestor of Hearthstone — may have attempted a similar system back in the day, but don’t quote me on that). I honestly do hope it works in their favor, and that they keep refining it as time goes on.
Tl;dr — I care too much about card games.