If you're talking about an engine with basic game mechanics, then no, the art is completely unnecessary until later.
However, I like to start with the art for my game. First of all, it's something relaxing and not that frustrating, unlike code. Secondly, it gives you an idea for what kind of setting you're game is going to be taking place in, which is useful for later coding things correctly, and also design of the story, and levels, and so forth. Also, like Paul Eres said, there are some basic art/code relationships. For example, if you're game is going to be 2x (e.g.
http://wmp.comyr.com), then you'll need to make sure not to leave any 1px holes anywhere in your engine or it'll look terrible. Additionally, you're going to have to make a lot of changes in your engine in order to make the art
work in the game. Let's say, for example, that the art you're given has grass clumps as tiles that go over the player sprite. You'll have to change your code so that it draws the grass automatically at the right depth, and sometimes editing your engine isn't...the friendliest thing, especially if you're a messy coder (I speak from experience).
A nice option if you're not very artistically inclined is to make a texture pack interface with your own polygons/programmer art as the first tileset/texture pack. That way, when you meet an artist sometime, you just give him that one file and tell him to put his own art in. Then you just exchange the old file for the new file and, boom! Almost no work required. This is also from experience. Tilesets are cool.
Edit: Clarity.
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