I tend to agree with the sentiment that Doom 3 was unimaginative and fairly boring.
Dear Id:
Stop wasting development cycles on cutscenes, dialog, and story. No one plays Doom for the plot. A red key is still a red key whether it's an actual red key or a password to get into the computer to hack the mechanism to unlock the door.
Go back to what made Doom fun: lots of monsters (on the screen at the same time), scary environments (that doesn't just mean dark), tension, gore, lots of secrets, monsters fighting other monsters, and fast paced deathmatch.
You know why Painkiller was a million times better than Doom 3 and Quake 4? See above.