Were Final Fantasy I's additional dungeons a good fit to the game?

I'm playing through FFI for the first time, and I'm accidentally stumbling into dungeons where it seems ridiculously difficult. I've now learned that they were add-ons introduced in later releases, and to me they seem a bit strange. Like going into Hellfire Chasm too early and getting absolutely depleted of MP. I made it out to the dungeon's overworld but couldn't actually leave or tent and was just super confused and frustrated at that point.

Towards the end I wandered into Labyrinth of Time thinking that was the end game, and again it was a one way trip into a super frustrating experience that wasn't fun at all.

I half wonder if they introduced these changes for people who were already familiar with FFI and wanted something new to see. To me, it seemed like it would have been better if they were harder to find, or had conditions to enter, like a sealed dungeon so that you don't just accidentally dig yourself into a big hole.