On the other hand, assuming both DRG and BLM loose their respective buff (stun or phase transition for instance) DRG jump CD are still refreshing allowing you do quickly reach nastrond stance (dunno the name), a BLM would need to start all over again.

I honestly don't think tour qol is required. I think it is fine that some transition make you loose your momentum, this is anyway compensated by CD refreshing etc.

Im no DRG expert but I hardly find botdg to be an inconvenience, yes there will be time where I'll loose it (all transition mostly), but the same is true for most job. Your example with BLM is also not very good as sometime while you'd be able to keep transposing, you'd still loose a fester because youd be enable to simply use it on anything (mostly happen in dungeon tho)