... And interrupting me with your bullshit while I'm unraveling an international conspiracy is not one of them!
Yes, I'm playing Deus Ex: Human Revolution. It's really great, but man, switching gears from the main plot to do the sidequests felt wrong. The narrative focus was always on the main plot, the energy always high, the consequences always severe. Allowing the player to stop and smell the sidequest roses seemed like a betrayal of the story and the world, and of the sense of urgency the game had created.
DEHR is not alone in this: Mass Effect 1 & 2 also come to mind as having silly, inappropriate sidequests.
What I'm trying to say is: some games should not have sidequests. The resources going into them should be spun into making more branching paths for the main quest, or something. With some games, the narrative is so propulsive that sidequests become plainly silly. The universe is about to be gangbanged by Reapers? Let's take some time out of stopping them to arbitrate this pointless municipal conflict!
With some games sidequests fit right in, of course. The Elder Scrolls games are designed around a free open world in which to do sidequests. That works well. Some games deliberately include breaks in the main story ("we can't do anything right now, we need to wait to hear more information") to justify letting the player go do their own thing for a while. That's fine.
But my machine-man hot on the trail of the people who destroyed his company and killed his girlfriend, a man capable of spitting out a radius of lethal explosives on command, shouldn't be asked to stop so he can punch some 2-bit gangster in the mouth.