Because it preserves angles, the Mercator projection also preserves shapes. Humans are generally pretty good at recognizing shapes but bad at estimating areas. As a result, the Mercator is going to look more like what you see on a globe at first glance than most other quadrangular projections.
The two biggest applications for maps, both now and in the past, have been navigation and land surveying. And only the former has any use for maps of large areas of the world, which meant that large scale maps of the world have long been dominated by navigation-centric projections… like the Mercator.
