Ramps are not just intended for persons in wheelchairs. They improve access for people with less serious mobility issues such as those with knee or hip problems or elderly people who simply lack the upper body strength to confidently support themselves using a handrail. Forcing such people into stair climbing chairs is absurd...and of cost far more costly than a few ramps or proper architectural design.
On modern buildings of course you want to build a ramp. But the cost of adding ramps to every already-built place accessible only by stairs is extremely high. At any rate, that isn't to say that it shouldn't be paid, in many cases, just that it's better (when possible and feasible) to develop technologies that let the disabled deal with it themselves. There are buildings with stairs and ramps or elevators. If you're disabled, it's good to be able to access these buildings when you come across them.
Along the same lines, the purpose of accessible digital text isn't only to help the blind, it's also to help the dyslexic and who knows who else, and generally facilitate content extraction software of all types. It's good when to do when it's feasible, but it's better to not have to rely on people doing it.
And they're a lifesaver when handling a couple of large suitcases! I can't believe how many cities and places neglect to soften the edges for bicycles, travelers, or people carrying stuff. The train stations that have plenty of stairs and no ramp to go around are especially annoying.
