Some of my favorite parts of One DnD are the things that Larian already changed. Starting proficiencies tied to class instead of race? Perfect. Physical features tied to race seems fine to me, i.e. elemental resistances or a free spell or 2. But linking proficiencies limited your choices when creating a new character. Some races were just built better for some classes and some are built really poorly for some classes. That was the first thing they fixed and it made me happy. WotC knows that the majority of people just want a streamlined way to have fun when playing without having to do hours of research and they're clearly moving in that direction. If you want to have a fun game with a large player base, the entry fee needs to be reasonable. I love 5e but when I was first learning the rules and making a character, I realized that if I wanted to actually be happy with my character months later I would need to spend a lot of time planning. If you don't already know all the features and how they work with/against each other, it's real easy to find yourself with an ineffective member of the party if you're just picking whatever feels fun at the time. That can put a lot of people off and the new edition is fixing a lot of that by basically including a lot of house rule stuff that people were already doing to make their own games more fun.

You can beat BG3 on Tactician with a jank-ass build tho. You don't need to do anything "competitive" if you play well. Great Weapon Master is definitely not necessary in BG3.

Source: I beat it on Tactician with a jank-ass build and didn't respec or multiclass any companions at all. Didn't even bring a wizard. Just Wyll (melee even!), Karlach, Sheart, and my bard.

Don't think 4e would have been a mess. It was a streamlined "computergamey" edition that wasn't that well received, hence the creation of Pathfinder. It had a vastly different approach to the battlefield forcing it to be dynamic. So many abilities moving a target in one way or another. As a skirmish game it is pretty neat but severely lacks in the roleplaying department.

Have you considered mods? Extra feat at first level could give you the edge you want.