As long as you're within the design width range of the tire, there's nothing wrong with it. Most 235's are designed around an 8 or 8.5" wide tire these days, and "acceptable" fitments go up to 9 or 9.5 on a lot of performance tires, especially with a profile as low as 40%.
I'd agree though that stretching tires past their design range is pretty dumb, especially since new tires have stiffened sidewalls that make that it dangerous and unnecessary. It may have worked back when "low profile" tires were 65 or 70, and everyone switched from stiff bias ply tires to radials with soft sidewalls, but tire design has progressed.
Choosing where in the "acceptable rim width" range you want to be is really a tradeoff - for a given tire, the "design width" is the rim width that will give maximum cornering traction. For the same tire, a narrower rim will plant and give better straight line traction, but it will be mushy in the corners, which means progressive breakaway but less driver feedback. A wider rim will stiffen up the sidewall, and give excellent quick response, more accurate turnin and better tactile feedback, but you will sacrifice grip in both acceleration and cornering. The tradeoff is between maximum grip and the ability of the driver to control the car on the appropriate line.