I've beat Garland on level 2 on FF DoS. Though that was only because I had fought 3 groups of Goblins on my way to the Temple of Fiends/Chaos. That instantly leveled me to 3. Beating Garland on level 3 is completely normal in NES, WSC and PSX and I do it very often. It's still possible on level 2 in NES/WSC/PSX and maybe even level 1 if you have a strong party.
FF1 DoS seems very easy, yeah, but FF1 PSX Easy is also quite smooth sailing. Except in FF1 DoS, you can save anywhere. Then again, bosses have been made stronger and there's the extra four dungeons, but those dungeons are totally optional.
I don't know what's so hard about FF1 PSX on Normal. It felt just the same for me as the WSC version. The enemy encounter things and bosses having double HP is the same in both WSC and PSX, and the same for all the items and equipment. Ice Cave is very dangerous and hard in WSC and PSX, even harder than in NES, probably because the monster encounter system is different and you might run into a group of 3 mages or sorcerers that just ambush you and kill your party before you get a single turn. Since enemies have double HP and they're more dangerous in WSC and PSX, those versions might be harder than the original NES version, but NES had very limited equipment space, some spells like Steel and Saber didn't even work IIRC, and it takes forever to buy 99 of the same item.