Honestly, I don't really mind that barrelmancy is a thing, didn't care much in DoS2, don't care too much here, though I do think there should be a way of severely limiting it. Best way I can think of personally is just make it something that one has to pretty much optimize/spec entirely into doing to make it even remotely feasible, insanely high strength requirement, heavy weight, that sort of thing. And while I wouldn't say I've ever felt this game in particular, or DoS2 was really built around the idea that you would abuse barrels, there's no doubting that they do take the possibility into account, considering stuff like Dallis/Bishop in Fort Joy, and the fact there is actual rewards and interactions for defeating them at that early juncture of the game. Takes significant set up of course, either with Deathfog barrel cheese, or other gratuitous use of barrels among other strategies, but really to me that's just fine as for those types of players who want to do something like that, the option exists.
The problem would be if they DO start balancing heavily around barrel use, rather than having it as an option that we'd have a major issue, which I wouldn't say is really a problem as of currently, and there is plenty of other sorts of "cheese" you can do to one shot particularly challenging fights among other things, like being able to kill the entire Githyanki patrol in just one turn as something like a rogue. Tons of set up, and no doubt a fair bit of trial and error, but that's just optimizing the systems in place really to give yourself the largest advantage possible, something that's pretty typical in almost any RPG I've played.
All that said though, I don't think its a major issue to see it heavily hampered, or nearly removed from the game in its current state, as overall I'd say it makes for a better experience overall, though completely removing it I feel would be just as harmful in the sense that it'd be actively removing a very real way of playing the game, even if its one that utterly exploits the systems in place.
All in all, I'm sure modders will manage to change this if there is enough of a demand to make it a more prevalent thing, so its largely a non-issue in the end, and is hardly going to put an end to cheesy and more exploit heavy styles of play.
