From a certain respect, there are 2 extremes when it comes to cylindrical map projections. On the one hand there is the Mercator https://en.wikipedia.org/wiki/Mercator_projection#:~:text=The%20Mercator%20projection%20(%2Fm%C9%99r,cartographer%20Gerardus%20Mercator%20in%201569 which is conformal and preserves local directions and shapes. The main downside is that, as mentioned above, this projection distorts the size extremely heavily at the poles. Now, this map already cuts off a good chunk of the north and south poles, but land in the northern latitudes is still significantly larger than similarly sized land at the equator and much of this land is the barren north of Canada and Russia. We could cut this off but we are limited by the northernmost piece of Scandinavia unless you want to cut off the top of the peninsula.

The other extreme is the Gall-Peter's projection which preserves size but not shape. https://en.wikipedia.org/wiki/Gall%E2%80%93Peters_projection. This shrinks the northern latitudes shrink significantly and shows just how ginormous Africa truly is. The entire globe also looks extremely stretched vertically and Europe ends up absolutely tiny.

The equirectangular projection is a compromise between the two https://en.wikipedia.org/wiki/Equirectangular_projection. It doesn't distort the north nearly as bad as the Mercator projection but also doesn't squish Europe the way the Gall-Peter's projection does. It's also the standard for global raster datasets and is used primarily in thematic mapping, which this is.

Essentially, the map people are most used to is the Mercator map. Anything else is going to look weird even if it's at least as accurate as the Mercator projection. Using this projection shifts more map area from the northern and southern latitudes to the equator which lets us put more detail into regions like Mesoamerica, West Africa, India, Indochina, and Indonesia.