I was thinking more along the lines of they should spend the extra 10min per bulkhead to build a proper "node" with the L-channel at the center of each bulkhead. That would let them use lighter (cheaper) material and have equal or greater strength. This is more important for a pontoon resting on the bottom because than one floating. When the guy cutting the channel is making $15USD/hr it's cheaper just to buy overkill material. When the guy cutting the material is making whatever they make in India it's worth it to have him spend the extra few minutes to put the proper angles on the ends.

I mean yeah, it probably is all overkill but I'm used to having to build things that have to withstand high dynamic loading so when it comes to mostly static objects I tend to over build things.