Don't like it, don't use it. As Boromir would say...
Is it an exploit? No, I don't think so.
Is it cheating? Well, if you allow (solo) you are only cheating yourself, I don't see it as a problem.
Is it fun? Can be, absolutely. Who can't be impressed with the Goblin army walking into a clearly marked minefield and at the work to set up such a trap? I use the same 'exploit' to kill the Cambions on the Nautiloid and start the game at level 3. Just means I'm capped so much faster. Also means or at least suggests I've played through a few times and am playing with stuff while I wait for Act 2. It's also a way to find bugs and unexpected behaviour.
Could you get away with it in real time games? Could you heck.
Could you get away with it in tabletop gaming? Good luck with that.
Could Larian do better? Why yes, they can...
The mimic idea is fun, but won't stop barrelmancy, won't stop the above, or this:
What could liven up things would be:
Add appropriate levels of instability and volatility to them:
Nautiloid tanks are basically rocket fuel. Oil is flammable, a barrel of oil is an impromptu bomb (though shrapnel damage is not applied to rolls) Firewine is similar and seemingly more flammable and can be compared to brandy. Gunpowder is (well can be) an explosive in it's own right.
Coding aside, the question here is cause and effect. A tin of gunpowder poured on the floor will burn, but won't explode. In a tin, with a cord fuse, it's a bomb. Drop a barrel of oil, it might split, but it won't explode, a steel barrel, leaking, causing a spark when you drop it, will. You get the idea.
(I've worked in the chemival industry, I know a thing or two...)
So, carrying them should be fine.
Dropping them can be assumed to be placing them carefully. But arguably with nautiloid tanks, should be chance.
Getting knocked down, with carrying them, there should be a corresponding chance for them to shatter (covering you in flammable fuel) or even explode.
If you are knocked down into flames... BOOM.
If you are hit, whether a spell, a flaming arrow, again, BOOM.
That's carrying them.
Now, imagine you are in the Goblin camp and decide to strategically place 50 barrels of explosives... (Been there, down that, great fun!) If oyu are on good terms, no-one bats an eye. Not even when you steal the Zhentarim's entire stash and drop it in front of them.
Now, all of this ignores encumbrance. So, add encumbrance
These barrels will be massively unwieldy. You could carry one, in both arms, you could roll or walk them. You could not stick a couple in a backpack, much less a couch.
So, first check would be, 'carry' - so a barrel in code terms would be treated as a two-handed weapon. (e.g. It shows you carrying (wielding) a barrel, but you can't attack with it). You could not climb a ladder with it. You could not leap with it.
Second then is, "OYE! What the bloody hell are you doing?" Because I am pretty such surrounding High Priestess Gut with barrels of gunpowder would be considered an aggressive act.
There are ways, and it would be great if Larian added them, sometime. But until then, have fun. Be creative. Blow shit up
