Yes. But we have the Doom1/2, Heretic1, Hexen1, SystemShock1, DukeNukem3D, Blood1, ShadowWarrior and even more.
All of those games are technically able to be ported to the GP2x at very good speeds. And they are a great games if not better than the newest one when we focus on the gameplay. And this is the 
thing and the most important.
The Chasm shows an IDsoftware wasn't really using the machines to a full capabilities. There are always places for an improvements small or big.
And not forget not all of us are so old to remeber (and was playing) the old games. There are many new younger people and there is definitely a market for them! Is an a "JumpingJack" (for an example) obsolete then?
No, it's not. We (the "oldtimers") are tired of those games but the younger ones don't have to. I even will be risking to say there is a big hole not fulfilled by current games industry.
Yeah, prove me wrong, criticize as much you want but why should we reinventing the wheel for another time?