I do think designers can go over the top. I could tell you stories. On the other hand, there is some line between design doesn't matter and "can't you see the difference between the two shades of black in this poster?" (Which is one of those stories.)

I should say as well that I've spent a fair bit of time in Asia and, to my Western eyes, a lot of conference materials look amateurish and make my eyes bleed. Maybe it doesn't matter much at the end of the day but I think it does at some level.