I specified it's the lowest you can go without downgrading and losing INT+VIT, but as @Sayori said, 700 sps is not much better, maybe you gain 1m on that 15m battery, but the main point of contention here is that Lucid Dreaming doesn't do enough to let you gain MP faster than you spend it.
Also remember that this isn't SB anymore, so 1000sps only puts you at 2.43GCD, which is nowhere near a BLM set for example. The BiS for RDM in SB's last patch put it at 2.47GCD, I don't think we're starved on MP because of 0.04s.
On a different note, this goes without saying, but I'd like to point out that while with constant uptime we're on constant MP loss, every fight has some downtime.
Right now RDM doesn't feel extremely bad because both Titania EX and Innocence EX have attacks and mechanics that either make them untargetable or require you to break uptime briefly, so you can finish a fight with more than half your MP to go.
This is all liable to change depending on future content, which without going into spoilers is going to feature at least one EX fight with quite a bit of AOE required, which costs even more MP.
Another big issue is that without on-demand Verraise the job really has nothing at all going for it (except dashing looks).
It is the lowest performer in raw damage, if you exclude the 2 jobs whose main role is huge raid utility, NIN and DNC, its one raid utility in the form of Embolden is still completely useless and even if it was good it would force the job to be in physical damage compositions with a SAM and DRG, and on top of that now it has also lost its one niche of being a res-bot in progression.
Big disclaimer: You can still clear on RDM, it is obviously viable, BUT there is absolutely zero reason to pick it over anything else.
If the MP starvation is part of the design I'm okay with that, Verraise was too strong anyway (and it admittedly doesn't fit the job's fantasy), but at least let RDM be a good support DPS, give us a decent Embolden, and some middle of the pack damage potential.
Right now we're a jack of no trade at all.