Acoustic Guitar Construction

I totally buy into the reasoning behind the use of reverse round kerfing and therefore I use it.

But, with all the talk about stiffening the sides and different kerfing styles that affect that stiffness and all that, I wonder why we don't just makes the sides thicker? Is it because it makes the bending too difficult?

Yeah. Pretty much. I bent black limba at .100" but normally that is considered thick.

Two reasons, bending and weight, the finished weight of an instrument is an aspect often overlooked by many. One of my early guitars used fairly thick cocobolo back and sides (90 thou) and it weighs a ton, although it plays beautifully and sounds rich and harmonious, it isn't a guitar that gets picked up as a go to.
Thinner sides with stiffeners are easily strong enough for the intended purpose imo.

Bob

I believe "Rick Turner" and "Charles Fox" have experimented with hefty rimmed guitars. For me its a matter of favorable bending thickness -- the fact is, with thicker side blanks cracks are more likely.