Sir Hillary and Mr. Norgay were brave and hardy explorers. They conquered what was considered to be unconquerable. The proved it could be done. However, those who are following in their tracks are not proving anything but that they can afford the equipment and hire the people who know how to do the climb. Indeed, these hired hands do the climb often enough to be used to it. They do it to earn the money of these so called "explorers" who are merely following along in the footsteps of those who earned fame. These followers are doing nothing but helping to despoil a previously untourched and majestic part of our world.
No, the first assent of Everest did not start a tidal wave of unsustainable expeditions to Everest, because people were going to want to climb Everest anyways. Everest will always have appeal because it is the tallest mountain that there is. There will always be explorers who want to do the ultimate thing.
I believe the first two who got to the summit showed that it was possible, but still very, very challenging. i think that the increase it travel agencies that cater to hopefuls started the tidal wave. The ease at which sherpas can be bought and used as guides even against their better judgement is what has created the increasing number of deaths on this mountain.
The first assent of Sir Edmund Hillary and Tenzing Norgay continued a long tradition of discovery and adventure that many thought would stop because so many places in the world had already been discovered. Now people could go straight up into the mountains as they had already explored continents and oceans.