I feel SMRPG Remastered was being balanced around the fact that kids may not want to do every fight, and actually go out of their way to avoid them. Even if the old game wasn't that hard if you actually fought all the enemies, it could still be kinda challenging (especially to a kid) if you ran away or just avoided fights. While also making the battles have a bit more reward for good play.
It does break the balance for the main story if you're an older gamer who likes to fight a lot, but it is a bit of a flaw of how simple the original SMRPG is in that there isn't much you can do to make the game harder other than avoiding fights or not equipping better equipment. (And I'd argue that doesn't make the fights harder, just longer and you end up missing content for the sake of it.)
TTYD on the other hand has the badge system to give players more flexibility so unless Nintendo outright demolishes your ability to equip risk reward badges I can't see how any changes they make to difficulty be worse than SMRPG.