I think the whole idea of bracketed tournaments is basically to weed out everyone except the two best players, then have them play one set for the vast majority of the cheese.
Some facts of life that tournament players understand:
1. On any given sunday anyone can win, so it's about who's playing better today, not who is the best on some absolute level.
2. Even if you really want to know who's best, it's not practical because you need a long race to determine the best player at any stage of the tournament. But then it would take forever. So players accept that the races may be too short to be 100% fair, and sometimes the better player doesn't win.
3. The top two guys, if they both know they're close in skill, may arrange a saver, in which case it doesn't matter which is #1 and which is #2.
With those things in mind, a single race at the end makes sense. We want #1 and #2 to play each other in a short race to see who is playing better today, and that's what you get in modified double elimination. Yes, one guy lost on his way to the finals. But that doesn't mean he's an inferior player and now has to play a second set to 'prove himself'. It could have been bad rolls, a random skid, a miscue, etc. Both players understand that.
They also know that even if the undefeated guy loses, then goes on to win a final rubber match, it's still a bit of a tossup who deserved the bulk of the cash. Two short races is not the same as one long race.