To Square Enix, these are the reasons why I am currently unsubbed from the FF14.

[Reynhart]

He said DRK had increased the number of tanks playing. So which is it? DRK had no effect on how many played tanks or it didn't? They can't both be true.

Quoting this article

The reason for the choice is that data showed players who played a tank or healer as their main class pre-Heavensward kept those jobs and new players didn’t flock to the roles.

I also found this interview, which adressed the situation in a slighty different way :

Looking at it from a role balance perspective, our data shows that the percentage of players who prefer tanks is about 22%, while healers are at 21%. Of course, ideally it would be nice if it was closer to 25% for each of those roles, but it’s still very close to that, so we feel that there is no point in trying to force people into doing something they don’t enjoy.

[Ariane]

Quoting this article

I also found this interview, which adressed the situation in a slighty different way :

You should look at this one.

Yoshida: The delay for tanks is longer in Void Ark because the addition of dark knight has had the effect of more players adventuring as tanks. Also, many players queue as tank to get a shorter waiting time, but since only three tanks are needed for Void Ark, it actually results in a longer wait.

[Reynhart]

What if, as a DPS-only player, you only have about 1 hour per day to play? With the current queue times, that's roughly 2 Sigmascape runs (or Trial roulette), 1 Roulette (other than trial), or 0 Rabanastre runs (Yes, that's a zero, for being over an hour total). All of that, combined with perhaps not even being able to play every day, means that someone with that kind of time constraints may have to choose between Sigmascape and capping tomes.

If you have that little time to play and are bored of simply capping tomestones (Can't blame anyone on that one ) then, yes, it's a bit harsh.

You should look at this one.

At 3.1, DRK, AST and MCH were still "fresh". Yoshida stated that lots of players jumped on the new jobs, but once the novelty was passed, most people were back to their usual role.