I like that many posts here in this thread oversimplify job comparisons to make them look more similar than they actually are.
Viper is just 123? What? No it isn't. Yes, they are 3 step combos, put onto 2 buttons, that change as you go through, with a mandatory oGCD you have to hit or you lose it. Each one also has separate buffs that dictate the flow of how you go through them. MCH is a straight 123, each hit increases heat and get battery on the last hit. I would hardly call them the same.
PLD and GNB being similar? No. PLD's burst is the same for the most part, but the last 2-3 hits are dependant on where you are in your combo. GNB on the other hand, every even window, you enter with no cartridges, every odd window, you enter with full cartridges. This changes how you approach the burst phases before you even get into them.
Gap closers not available to melee jobs? All melee DPS have always had access to a gap closer. The only discrepancy was with tanks, with DRK having the first one, then WAR getting one in the next expansion then PLD the one after. However, in SB PLD did have access to a stronger ranged attack, which is likely why they didn't add one for PLD.
Gauges, I've seen this a lot. Just build and spend. Ok, name a gauge that isn't. Oh, Old SAM had some thought because Guren cost 50 Gauge and Shinten cost 25? You are still just building and spending, so I'm not seeing the benefit. You need to think about gauge building and spending to make sure you don't overcap whilst keeping enough for burst? So, you have given yourself an artificial floor, ideally, don't go below this and most of the time you will be fine.
I hope people see the irony in what I'm trying to portray there. I guarantee that if anyone makes a suggestion to make gauges 'more interesting', and I were to come back with, 'but, it is still just building and spending', people would likely get annoyed, I would say, rightly so as well. I'm taking all the nuance out of the system and oversimplifying it, to make everything sound the same. That sound very similar to the though process that people use to say all jobs play the same. Curious that.
EDIT:
It should be noted that I do feel the 2 minute meta has not been beneficial to job design. But not because every job has a 60 second and a 2 minute, but because it pushes out certain damage profiles, like more sustained DPS jobs. Monk, Summoner, Paladin, all more sustain orientated jobs in the past, but the 2 minute burst meta has necessarily forced them to fit the mould. In an ideal world, I would have jobs be more flexible, as an example, imagine Viper, but ignore the 2 minute meta. In theory, you could easily Reawaken whenever you wanted at no damage loss. The buffs are going to last though them no problem. However, what if the boss had a burst phase coming up. You could save it to help with that section. It might be that your group decides DPS 1 and 2 burst in this phase, whilst 3 and 4 hold it for after or use it before, to help with the overall fight DPS. A system like this, I think, would be better for the game and, since there are no strict burst phases every 2 minutes, your fights can be less rigid.