Actually there's more than just that. I liked the original Revelations on PS1 over the PSP port for several reasons:
- The soundtrack. It's more than just the right music, but also the stylish ending to every song, and the different variations of the songs when in non-battle areas in dungeons.
- Sound effects. There are plenty of sound effects missing in the PSP remake and they changed the demon voices for the worse.
- The "slow" animations. Lots of people will probably disagree and they're tired of watching the animations, but I personally think the slow animations when casting spells using personas are really stylistic and the fast movement in PSP version feels rushed.
- Dungeons: Save points rarity in the original was better in my opinion. It made you play carefully at all times. Also it felt forced to have shops in dungeons in the PSP version. The game just doesn't feel as demonic when you have shops in dungeons and in PS1 version you had to prepare beforehand. I strongly preferred the way you move in the city streets in the PS1 version as well. They made it too easy in the psp remake.
The main reasons for wanting the Japanese PS1 version translated is the difficulty increase, Snow Queen quest and last but not least the original non-westernized characters.