Jelan
Aquaman is dead lel
Not like there are a ton of people shouting Aquaman is sooooo good nowadays.If you're complaining about opening people up, you ain't throwing enough. it's a pretty big part of his gameplan (adds to his stagger game) something to keep em thinking. And when you actually land the hit your oki is pretty damn good. He's a defensive neutral character with good chip. He can make meterless manta ray safe dependent on spacing which means he's building tons of meter. People don't say "Aquaman is bad cuz no 50/50's" it's the same basic idea only Manta has better oki and mobility to compensate for the lack of tentacle. His counter zoning is good, he's got good buttons, good AAs, a STUPID jump in normal in J3, good chip, good meterbuild. Idk what else you'd want in a character like this.
TL;DR
Apparently defensive=bad unless you're aquaman.
Furthermor, Black Manta is 'fine'. As in he is not utter trash but not exceptional either so probably no changes in the foreseeable future.