ehhh... Doom 3's limitations were painfully obvious when it launched. The shadows and pure blacks were a nice stylistic workaround for handling only a single light source, but later levels went crazy with filling the world with glowing fog to make larger rooms even remotely usable. It felt more like an elaborate tech demo than a game at times.

It was a significant leap, but it was the right time for it. In less than a year you saw other games doing the same thing or better - they had clearly been working on it as well. Doom 3 was just the first to come out, and Carmack did a lot to spread knowledge about it immediately (as he frequently does, which is wonderful).