any point/reward for playing the classic maps?

[Ciaran Zagami]

even just progress towards 100% completition?

[talgaby]

Nothing apart from the satisfaction of playing them with the Doom 4 game mechanics. If you want them in more of their original state, there is a snapmap campaign recreating them.

[Phoenix]

It makes me want to play the original Doom again. That's always a good thing!