You're comparing apples and oranges, so to speak. Firebyrd's contribution is a set of platform tiles. The images you linked to use a complete tileset.

Wizetea's tileset isn't a good example to compare to Firebyrd's platforms. Instead, let's take a tileset I made a long time ago for example: I called it "kitchen sink". It was a picture of my sink, masked so it could be used as a level. There was only one level you could make with it. The picture covered the whole map. It looked okay, but had no functionality past making a single level.

Comparing Kitchen Sink and Firebyrd's platforms is comparing two extremes. A good tileset (also, most tilesets) contain both basic platforms that are easy to use (like Firebyrd's) and some fancy, pretty stuff to add variety. Both are important, and are used differently depending on the situation and levelbuilder's skill. A good tileset needs both. Asking which is better or more important is like asking whether we prefer the front or back wheel on our bicycle.