A lot of this does depend on the game in question and what it's trying to accomplish. Many of the old dungeon crawlers (Wizardry, Bard's Tale, PoR, Dungeon Master) placed a great deal of importance on the way their areas were laid out. Most of them were simple square grids, and since you moved one "square" at a time, it wasn't difficult to map them. Once you had a map, you could see which areas you hadn't explored yet, or discover hidden rooms. I'll never forget my pleasure at stumbling into a hidden treasure room in Pool of Radiance (in the slums!). You just would never have that surge of joy if you had just seen it on an automap (or clue book; Por's automap was crap). It was also just cool having a nice hand-made map, since you could take pride in that and being able to navigate the dungeons swiftly and accurately. By the time you were finished exploring the whole thing and making your map, you really knew that dungeon well. That's a very different kind of experience than just blowing through a dungeon, letting the automapper track your progress.

That said, I did often rely on official guide books for CRPGs, mostly because I wanted to experience the entire game. Sometimes I would go through a game once with no guides, and then again with a guide to make sure I had seen all the content. Later on I just decided to keep a guide handy, since I didn't want to miss out on anything cool.

In any case, mapping out many modern games would be very tricky, since few have the nice square grids. But I could see it in small doses--maybe have an automapper everywhere but in the dungeons. Some games have automappers as part of their magic systems, so you have to cast a spell or use a magic item in order to see the map. Anyway, I would rather have an automapper unless the developers have really worked to make map-making easy and worthwhile. Also, I don't think it would work well for real-time games; you'd need a turn-based setup with very discrete steps or movements.