A gondola ride to Everest would be awful. A quick ascent to that height would virtually guarantee some pretty awful side effects for most passengers. I certainly wouldn't want to be on it.
What makes the top of Everest interesting to visit is that to do it, a person has to overcome very difficult natural challenges. So a gondola to the top would destroy the very value it was supposed to provide.
It's not some trivial walk around the park just because it's not considered one of the hardest summits in the world.
As for whether or not the gondola would be a good thing, I guess that'd depend on a lot of feasibility studies and cost analysis (cost to the environment, to the local populations way of life, monetary costs).
Millions of people travel in commercial airliners every day, at altitudes greater than the summit of Everest.
The railroad cars offer enriched oxygen and supplemental oxygen, though they're not pressurized. Edema is a real possibility.
https://en.wikipedia.org/wiki/Qinghai%E2%80%93Tibet_Railway
Or this travelog:
http://www.sfgate.com/travel/article/HIGH-TRAIN-TO-TIBET-Wor...
As the altimeter approaches 17,000 feet, a package of potato chips balloons outward until it ruptures a seam. Sunscreen and hand sanitizer erupt unbidden from bottles. In soft sleeper class, Chinese businessmen sprawl listlessly on their bunks, sucking oxygen from plastic hoses. The bathrooms smell of vomit.