Increase the Skill Floor for Dungeons Next Expansion

[VerdeLuck]

a number of MMO developers have said and experienced the exact opposite of what you're saying based on ther experience and data. Increasing the difficulty of casual content does not make casual players play better or engage with harder content, it makes a significant portion of those that can't clear it just quit.
WoW just had an influx of interest with Dragonflight after going abck to making a good experience for casuals.
In Heavensward, SE added savage level weapons to Thordan EX and increased the difficulty along with it. This had the opposite effect of what you are saying, players who previously played EX Primals as their content for engame couldn't clear.
In Stormblood, the Ivalice raids significantly raised the bar for what was expected in alliance raids. Instead of rising to the higher difficulty, casual players just chose to not do or unlock the alliance raids that expansion. It took nerfs and a flat echo buff to Orbonne to get casuals to run it regularly again.

It seems like raiders in this game are of the mind that casual players should "git gud or leave the game" but in that scenario, they're gonna pick the "leave the game" option.