Is it worth pointing out that a wheel drops into a pothole bringing the upper arms bump stop into play? I suppose a stabilizer bar could bring the lower bump stop into play on the opposite side.
I'm not sure what point you're trying to make. The UCA bump stop limits suspension extension and the LCA bump stop limits compression. Pot holes can cause extension, but they also cause compression when the wheel hits the opposite edge of the hole and has to bounce back up onto the road surface. And every road surface variation isn't a hole, there are plenty of bumps too. Not to mention that hard braking causes suspension compression, as well as hard cornering. A nice downhill corner taken at speed can bottom the outside wheel's suspension. In my experience I've found the lower bump stops actually get used much more frequently than the uppers.
Some of the tubular UCA's out there don't address the fact that they don't line up with the upper bump stop either, which is a problem too.
And if you substantially lower a car and install really large torsion bars you have to use taller upper bump stops to keep the adjusting bolts from coming off the torsion bar adjusting arms at full extension because of the narrower range of adjustment the larger bars have. It makes sense though, when you lower the car you're changing the center point on the range of suspension travel. The large bar reduces the need for suspension travel on the compression side, which is used to lower the car, and the taller upper bump stop limits the extension to match the compression distance so the new ride height is still in the middle of the range of travel (which is now smaller).
