Early editions of D&D are often raked over the coals for being ammaturish in art quality. I will agree alot of the early art was rough. The early art was also very inspirational. Some of the most iconic pieces still inspire the artists of today to homage the early greats.
While the current crop of art gracing 4e materials and Pathfinder are definatly profesional, I find them lacking. The Dungeon punk look doesn't do it for me. Along with the Manga inspired style turn me right off.
There is such a thing as classics. Prefering the "classic" style of art of early D&D is where i stand.