I completely agree.
The status quo for most MMORPGs has always been 5-player groups: 1 Tank, 1 Healer, and 3 DPS. Even then, extraordinarily long DPS queue time has consistently been an issue across the board. It's completely ridiculous that FFXIV not only failed to acknowledge or address this dilemma -- it actually made a bad situation much worse, by reducing party size to require fewer DPS roles.
I've had queues on my DPS character that exceeded 75+ minutes. After grinding FATEs and Leves ad nauseum, I'd had enough, and just logged off in disgust. I don't understand how anyone but the most dedicated and determined Final Fantasy fans play a DPS class as their main at all. Indeed, if I didn't enjoy playing Healer as a main, I probably wouldn't be here now.
It's just common sense. If one role has instant queues, one has relatively short queues, and one role has extremely long queues, then obviously the proportion of players actually playing these roles is not accurately represented in the standard party make-up. Back in World of Warcraft, anybody could tell you that more than 3/5ths of people were playing DPS at any given time. I don't know how anybody ever got the idea that "No, it's probably less that 3/5ths, it's more like half." You'd have to be high as a kite.
It's probably too late to adjust previous dungeons without a near-total redesign, but there's no reason new content going forward couldn't easily be made with 3 DPS in mind.
To me the queue times are a serious class-balancing issue -- maybe not in terms of combat mechanics, but in a foundational, "meta" way. In an online game so heavily focused on dungeon and party content, I expect the fundamental composition of those parties to be considered carefully so as to be realistic and functional. By ignoring this core aspect of their game and pretending it doesn't exist, it kind of seems like they don't take the matter seriously and value their customers' time.