As long as there is a Tank, and Healer, the other 4 jobs in the party should not matter and SHOULD be able to perform and clear content intended for parties of that size.
If there is a new inclination of the DEV team to balance things out then it should be there goal to see all jobs included in end game content.
However, I feel that much of this is fueled by what people have found to be the optimal build for beating content. Once it is beat, then beaten easily, that is what everyone wants to do. What is the easy way out? Oh it is sending in MNK, RNG, SAM to pummel the S**T out of the monster before it gets of the mega move that can/will end the run as a failure. This is a most unfortunate thing, but it is a thing none the less. I always try to have a job ready that I have to play in order to the latest content, though I true love is BLM and I never get to go anywhere on that unless it is old content (sad fact) so I would love to see changes but no nerfs. Buffing up the other DD classes so they can be on the same level of the cookie cutter DD flavor of the time.