This was a time where, for 3D graphics, barriers to entry got low (math got figured out, hardware was good enough, knowledge spread), but the commercial market didn't yet capture everything. Hell, a bulk of those excited kids I remember, trying to do a better Unreal Tournament after school instead of homework (and almost succeeding!), they went on create and staff the next generation of commercial gamedev.
(Which is maybe why this period lasted for about as long as it takes for a schoolkid to grow up, graduate, and spend few years in the workforce doing the stuff they were so excited about.)
I was one of those kids, my focus was Marathon 2 even before I saw Unreal. I managed to figure out enough maths from scratch to end up with the basics of ray casting, but not enough at the time to realise the tricks needed to make that real time on a 75 MHz CPU… and then we all got OpenGL and I went through university where they explained the algorithms.
The era was people getting wowed from Wolfenstein (1992) to "about Halo or Half Life 2" (2001 or 2004).
And I'm not saying the flattening of excitement was for any specific reason, just that this was roughly when it stopped getting exciting — it might have been because the engines were good enough for 3D art styles beyond "as realistic as we can make it", but for all I know it was the War On Terror which changed the tone of press releases and how much the news in general cared. Or perhaps it was a culture shift which came with more people getting online and less media being printed on glossy paper and sold in newsagents.
Whatever the cause, it happened around that time.