The "no backgrounds," while probably iffy when you compare editions, is still a valid criticism of the artwork today. In the core books, to a certain extent, it's nessecary -- compare the WAR Terrasque in the DMGII with the one in the MM. The one in the MM shows me how a Terrasque looks. The DMGII one shows me how a Terrasque looks when it's kicking your ass. But if I didn't already have the MM pic, I'm sure it could be said that the DMGII pic gives you very little real idea of how the thing looks normally.
I have found that, for me, no backgrounds is why a lot of the modern art, while very good and quite evocative of a character, doesn't really stir my nature very often. It's not *inspiring.* And that's partially because a lotof them don't show scenes -- they show creatures, characters, effects, but only in a kind of text-book demonstration, not in situ. And while the textbook is almost essential for some of the creatures so we can tell what they look like, it still doesn't make me want to go out and use a Destrachan, for instance...it's just sitting there in the MM, not inspiring me to do anything with it...not attacking adventurers, not building his underground empire, not destroying castle walls with his harmonics...just kind of chilling there. Lookin' angry. Gr.
As a comparision, the half-elf on the airship platform, or something like the Neogi raid pictures in Lords of Madness, make me want to go out and run that scene RIGHT NOW. I want the PC's to arrive on an air dock, I want them to see the destruction of eel-spiders and umber hulks...I don't want them to face a Destrachan...
I guess there are two kinds of art: for the DM and for the Players. Players' art is characters, figures, etc. DM's art is encounters, events, dramatic happenings, etc...