One of the big problems with gating jobs behind content is that it prevents the possibility of being able to do that content *with* those jobs.
That issue doesn't apply to locking content behind content, though. I see no downsides to locking dungeons, trials, etc behind MSQ progress, just as the game has always done. It's essential anytime those dungeons relate to the story (as most should if they're going to have a purpose for being here). And certainly the new sections of MSQ should be gated behind previous ones. Unlocking new regions without MSQ requirements prevents the initial travel to those regions from being used as part of the story, so while (depending on the story) it might not always be essential to gate travel access, it's certainly valid to do so.
It's really just the jobs that would benefit from not being as deeply gated as they were for Heavensward. I also think unlocking those earlier would help calm the torrent of complaints about the rest of the MSQ gating. A few might still grumble about not being able to do the top tier raid immediately with their brand new underleveled character, but I think most would be happy with being able to try out the new jobs while they continue progressing through the MSQ on their way towards the new expansion's main content.