But... our dungeons are already Easy Mode. They can easly cleared by any party composition.

For everything but Coil there is an Easy Mode - the HW and SB raid tiers got Story Modes, so you dont have to do the difficult fights to see the story.

I'd only be okay with this if clearing the dungeons in Easy Mode meant that you have to clear them again in "Normal" (aka our current state) Mode to unlock them. I'm sorry to be so blunt, but I honestly dont want to have people in my later dungeons who didnt even cleared Sastash NM...

And sorry to be so blunt again, but: Considering the genre of this game you should either work on overcoming your anxiety (and "less-skilled" is no argument - work on that instead of trying to use it as an excuse not to play!) or look for a single player game.
The dungeons are easy - you can almost ignore every mechanic. We cleared one of the current endgame dungeons with a BLM who did maybe 20% of the damage they should have been doing a few days ago.

And I'm saying that as someone who spend the first 2 months with the game basically only crafting because I was to afraid of dungeons. Running from your problems isnt a solution. Its never a solution. Giving in to your anxiety is letting the anxiety win.

Btw: All dungeons up to level 60 can be done unsyched - so with any number from 1-4, while keeping your current level, making them a lot easier. So, if you really dont want to do them with DF, you can ask a higher level play to do them unsyched with you. It wont change the dungeon and its mechanics, but you can have a level 70 in Sastasha, one-shoting everything.
Re-designing all dungeons to match a super-baby-easy-mode because people dont want to improve is the wrong way to go. Specially because, again: The dungeons are already not that complicated or unforgiving when it comes to mechanics in the first place.