There is nothing inherently wrong about melee action games/brawlers with "one button" combat. Not every action games needs a Light and Heavy Attack combo. Look at games like No More Heroes 1 & 2 (III adds in L&H ATKs), Killer Is Dead, or even the first Devil May Cry. While these types of games may be more simplified in comparison to DMC, Bayonetta, NG, or even God of War (both eras in some cases), tat doesn't mean they lack mechanical depth or complexity. KiD has an attack button, a block/parry button, and a charge-stun and guard breaker button. Mondo's attacks can be upgraded to either cover greater distances or gives him new moves. Even his charge attacks can be upgraded and has an upgrade where if you counter an enemy, he'll perform a power gyser lift said enemy or anyone around it straight in the air for Mondo to wail on!
These mechanics come from somewhere and mutate from each other. Back in the arcade days and the 80s to 90s console era, many 2D brawlers have an attack button and jump button. That's it; the designers got creative and allowed players with direction inputs to pull off different moves, canned combos, and those will multiple playable characters (that weren't lazy/limited color swaps) all played and look completely different. There's a reason why Streets of Rage 2 still gets so much love. It already built off a decent combat system from its prequel. Back attack, tag-team throws, and vaulting over any a mook. The sequel did more. They added health draining moves to button that has two different inputs: neutral and forward direction. The Blitz Attacks do the same thing, minus the health draining.
Ninja Warriors (1994 SNES Remake) may have only two attack buttons and is on a single plan, but the genius lunatics at Natsume managed to have all three characters have their own inputs and Street Fighter style commands. Each character even have their own hidden moves the player has to figure out on their own. They can all block too by holding the attack button. The remake to the remake, Ninja Warriors Once Again (Ninja Saviors) take this even further with giving each character EX attacks, new juggle moves, and with even certain characters pulling off air combos!
This stems from Serpahim17 back in the early 2010s when he mentioned El Shaddai in one of his walkthroughs and how didn't like the game, because of its "one button" combat, and how any game like that is "too simple". I'm not the biggest fan of the game either, but that is not always the case, and is ignorant to say. You may not like it, but others do and can see the mechanical depth. Once again, not everything needs to be exactly like DMC or the other high caliber action games.