His output does increases.
Learn how gear 4 works. Luffy uses all his Haki at once for gear 4. More haki is poured into each strike. That's why luffy goes inti cookdown of not being able to use haki after using gear 4.
Sanji's output wouldn't increase with hotter flames???
He's simply perma using his Haki, that's why he's only able to maintain this form for 30 minutes before it's all out. It's a fact Sanji has to maintain the Haki + exo combination to maintain the flames. It's basically the same concept.
Again same dumb argument. Why not just give him Stronger Haki, because that's what would happen if he unlocks conqueror. What was the entire point of exoskeleton.
Because it wasn't necessary atp to get ACoC? Sanji had to accept his identity as a modified human and that's why he got exo + IJ. It was meant to surpass the combined technology of his father who's responsible for Sanji's suffering. He fought against an opponent who was capable to use all techniques of the Germa as a single cyborg.
Now in this arc, Sanji will unlock his true potential to fight against immortal demonic enemies who can only be damaged by ACoC. Again, where's the issue?
Plus, technically, Sanji could even imbue his exoskeleton with CoC, creating even far hotter flames than IJ. His exoskeleton is a very useful PU, it proves he isn't overly reliant on Haki, he's pretty much an allrounder who has DF-like powers but can swim. An ACoC Sanji seems to be pretty strong tbh.