The chunk of negativity isn't even widespread, it's purely directed by 5e DnD cultists who think their dice marathon gameplay makes for a superior experience to Divinity.
I'm not a D&D 5 purist at all but I think that a better balance between Larian's homebrewed and D&D would lead to a superior experience to Divinity.
Is that negativity ?
I can already tell his video likely involved several save reloading in case the dice rolls didn't favor him.
It's absolutely abysmal videogame design. Keep that crap for tabletop trolling with friends; this design has no place in a single player RPG videogame experience.
Their biggest mistake is trying to please the 5e crowd, which will be insatiable and only cares for strict adherence to their sacred book regardless of how many potential players not interested in 5e tabletop play it alienates. They should have kept the Forgotten Realms IP and storytelling and discarded the awful 5e in favor of creating their own cRPG game, which has brought them to the financial success that they are by this point.
This video is boring because he's playing a solo cleric.
Being able to play a solo cleric easily in a normal game mode shouldn't be possible.
On the other hand, encounters aren't designed to play with a solo character. Of course missing once twice is boring...
But did you really play any other TB games ?
This has nothing to do with D&D.
The video is boring because you know the outcome of that fight is down to a dice roll. He was able to survive that solo fight because with Light Cleric's passive of imposed disadvantage on enemies plus his heightened AC, he had a better dice roll to dodge the Iron Foots that would have 2 shot him several times.
But it's just that, if the dice roll had not gone his way, the video would have been over in less than 40 seconds.
Including his entire party doesn't make it more interesting. If you're playing without the vaunted "homebrew", it boils down to a bunch of actions with 50-70% hit chance, and about half your playtime spent missing attacks and hoping the same applies to the enemy so you don't eat an attack for more than half your health from a single enemy.
And it's not just the combat, putting down dialogue outcomes down to dice rolls is horrid design as well, meant to rob you of playtime by having you play the save reload game wasting your time on asinine mechanics.
I wouldn't be surprised if some modder manages to delete the awful dice a rama casino play off the game, but it shouldn't take a modder to realize that playing the game in 7-10+ individual participant turns with a single action turn where half the abilities miss makes for a deplorable gameplay experience.
People like to be in control of the outcomes through their own decisions, not have the outcome of a fight drastically come down to the roll of a dice.