I haven't seen too much problem with this. Yes, they can do a lot of damage. But that's kinda the point of shooting barrels full of high-explosives, isn't it? They usually aren't too hard to avoid walking near, and can be set off from a distance, moved from where the choke point is, and teleported around. I've only died to barrels a handful of times (out of many, many deaths), and rarely even die from them on the 'barrel hell' levels, and I'm not even a great player (no wins over HNTR).