The OPs remark is to bias, he list things that are of course easy because that's what the devs designed them for. Dungeon are easy because they are just a tool to help people catch up. MSQ is easy because it's meant to be enjoyed, but hey even then it's inaccurate to say MSQ is easy, recall the last DF based fight we had in MSQ last VU? That was somewhat hard before people understood the mechanics. As for Job quest, same deal, no point trying to micro-manage difficulty with a singular instance that players only go through once with their character, it's just a fun narrative for your job.

Overall your statement would work better if you provide the full run-down of all current content and the diversity of who it caters to, because honestly, I think it's rather balanced atm. When Diadem 2.0 comes around it might have a better balance because it would have content that caters to the midcore players and POTD is the first step in "Deep Dungeon" content to provide that tough content people are asking for in dungeons.

Truth is, in the current dungeon format that is set for catching up, you can never make them difficult because they fit a set linear design to make them easy to run however let me leave you with this question.

What if SE decided to only release 1 "Extreme" Dungeon per patch however they also introduced a Mini-Deep Dungeon for those that want a slice of randomness thrown into their runs. So rather than design 2 linear dungeons they design 1 linear dungeon that casual players can go through and then provide an RNG dungeon for those that want something random. It could just be a bite-size 10-floor design dungeon with it's own unique gimmicks that vary traps, unique mini-bosses and bosses. There could be 2 designs for these dungeon types, a Matched-setting that provides a linear RNG narrative that changes with each run and a fixed-party setting that gives the group of 4 a unique path to choose which route they want to take to complete the objective.

You could say that this matched RNG-dungeon would provide the same difficulty curve as the normal dungeon but the mob types, potential gimmicks and even bosses would vary. Meanwhile the fixed-party group would provide players with the opportunity to adjust the difficulty based on how they feel, taking certian paths that are only open as long as they have less than 0 KO party wide or reach a certain location in X amount of time, or find a secret that leads them to opening a hidden area to move forward.

I think things like that could be fun, if people didn't mind SE splitting their current 2 dungeon resources into 1 dungeon and 1 RNG dungeon with POTD inspiration.