It's often hard to make them accessible, though :(
Agreed. Not only that, but if they are accessible, the ramps can add another 100 yards of walking or so. I timed it out once, and a full cycle of the lights occurred during the time that it took to cross the ramp.
I used to use a pedestrian bridge that had a circular ramp to get up both sides and an elevator. The elevator needed a key though, so I guess you did have to know where and how to get the key if you need to use the elevator.
Also, the constant stairs are a huge annoyance when you walk the city, especially if you have heavy things or any kind of wheeled thing with you. (And it also holds for ramps.)
Or how about just forcing cars around these busy intersections. When there is too many people, they should just ban cars from these areas.