In terms of carrying barrels - its fun to do it if you want and nobody is forcing you to carry them around - as far as I can tell the encounters are beatable without stacking barrels.
Can you stack them if you want - sure, why limit something that is optional.
The amount of surfaces is ok for me, albeit on the larger side.
Because even if you choose not to use them, there are so many that they inevitably go off from aoes, or enemies.
