However, the icons used should become an industry standard, and the sooner this happens, the sooner players will get used to them.

One more thing about icons: They are required when more than one function is mentioned on the box cover. The icons used are less of an issue. Most players are used to abstractions (e.g. wooden cubes for resources) and are unlikely to believe that a cogwheel stands for "mechanic" or "engineer".

It may even be a good marketing decision for a publisher to mention only the designer. And it may be a good decision to mention both the designer and the illustrator. As a designer, I see publishers as partners who add their skills to make the most of my games, which is in both our interests.

An additional note: Showing more contributors than the designer on the box cover is not a yes or no thing. There may be games that had few contributions from anyone other than the designer. This is especially true for simpler games and card games, but not for many complex/expert games.