Gudadantza: Graphics always matter except in Interactive Fiction, Text Adventures, etc.
dtgreene: You can have an interactive fiction game with graphics, much like you can have an illustrated novel.
Also, one could make a graphic-less game that has RPG-style combat in it, getting an RPG that doesn't need graphics. Actually, it occurrec to me that Progress Quest could be considered an RPG that doesn't have graphics (and has the rather unusual characteristic of being a 0-player game).
There's also the possibility of audiogames, games where there's no graphics and the game conveys information to the player solely through audio. One way such a game could be made is to start with interactive fiction and record every single text message in the game, giving you an interactive audiobook that could be considered a game. (The quality of such a game depends on the creator's investment; using text-to-speech won't give the best results, but if professional voice actors are hired, the game could sound quite good.) I note that, in this instance, sound plays the role that graphics play in more conventional games.
Specially in Europe since the very beginning of Interactive fiction those kind of text games had graphics bundled as adding attractiveness or added value.
But exceptions aside, they could be deleted and the game could be functional per se. That's what I mean with the word importance. The spirit and sense of the game was the text and descriptions. In the other hand, other more modern and evolved IF examples where created with graphics in mind, to help the parser, like those Legend Interactive Adventures. But the fact was that you could convert the game in a pure text game and it was equally playable without any loss, just pressing a key. So, in fact even in those cases, the interactive graphics where only an attractive redundance, two ways to play the same game mixing graphics adventures or pure text adventure ad player taste.
About the recorded games, it is a very interesting concept. Never thought much about it but it very interesting and experimental. specially for vision impairment persons. No idea if it exists as something noticeable. It should.
greetngs