No, the flexibility comes from the ability to double weave HJ + MD when you need to do a double life or when you start an encounter/new phase with 1 eye. The case of DSR is a bit different, it's done so that you can get a 2nd eye by the end of a phase that lasts around 32 seconds. With the 1s recast, this was extremely tight to get if your ping wasn't low.
In this case you often lose the GSK, but that loss is manageable vs losing an eye, and thus having to reopen the next phase with 1 eye, which is going force a HJ + MD double weave regardless, and will delay the burst, thus not allowing you to get yet another 2nd HJ before the boss leaves if that phase's duration is also around 30+ seconds.
This creates a chain reaction in which you will always be delayed or drifted and it may or may not be fixed by downtime (since your CDs are still ticking).
Sometimes 1s is enough to lose a use of HJ and thus an eye.
Another example can be found in the newest extreme trial. You must use HJ at least 1 GCD earlier than normal and not drift it by more than 1s or you'll end up drifting it for around 12s or more due to boss phasing, thus making the next parts annoying to deal with since you can get HJ back when you have to move away, or simply 'cuz having such a big difference between HJ and GSK can be problematic in order to keep life aligned with buffs. Again, a chain reaction that can't be fixed in this case because there's no more downtime and that can easily drift oGCDs out of buffs and/or make you lose a whole life window in the fight, which is catastrophic: 1700 oGCD potency not counting buffs.
I can return you the question. When have I said anything about the job's viability? People have not started playing DRG en masse just because it got HJ + MD merged. Let's be clear, it's one of the jobs with the lowest amount of actions having to be bound in the hotbar, and HJ and MD have been separated for all of their history except for 3 months.
Missing a potential eye that you could get due to clipping is not tiny loss, it's huge. Clipping in general can lead to huge losses, and it shouldn't exist on a job that has had its oGCDs' animation lock reduced precisely so that they can be double weaved.
Who said that you need to optimize to clear normal content? You can clear normal content with HJ + MD merged or not. That's beside the point.
Saying that having the ability to double weave most of our kit is dumbing it down makes no sense to me. We're a job that has a 2-min burst which requires us to do something like 8 GCDs with double weaves in every single one of them except Stardiver. The difficulty resides precisely in achieving this to perfection and putting all of those oGCDs within the 15s that Battle Litany lasts, making sure that we also get two NAS under it.
And in any case, removing the ability to double weave HJ + MD from most players unless your ping is low is, again, less flexibility. You shouldn't need to have low ping when you got to do this specific weave.
TL; DR. The HJ + MD brings flexibility and doesn't hurt anyone. The job has worked like that for all of its life except for 3 months. Button bloat concerns cannot be called in here when DRG has the least amount of actions requiring to be bound in the hotbars.