Perhaps you're (by that, I mean everyone) thinking about it the wrong way.
We know the region lockout was there not to "screw" us in the American market, but to prevent the "edited" U.S. versions from re-entering the Japanese market.
What if the alternate U.S. art was something that NEC Japan stipulated alongside the region lockout to prevent any sort of "regional" confusion? The "bad" art makes a lot more sense in this scenario, too. Say NEC of America is going to release these games, but Japan is mandating unique artwork. In true NEC of America (later TTi) form, they farm the work out to the cheapest session artists they can find and the rest is history.