This was basically what was suggested by catch over in #1939660-10: Use YAML as the primary means for service registration and I have really come around to this idea.
Right now we have a class defined by Symfony, on which we call one method when building the container - we can call a method on any class we like to do the same thing.
IRC conversation with Crell today:
katbailey: Crell: bundles as they are now are just container futzers - maybe we get some processing of them for free by the kernel but I'm not sure that's worth the confusion
[1:37pm] Crell: Confusing with Entity API or with Symfony?
[1:37pm] katbailey: both!
[1:37pm] katbailey: symfony bundles are a lot more than container futzing, we don't support any of the rest of it
[1:37pm] Crell: Entity API's naming is dumb to begin with and we've been trying to change it for a year, so no biggie there.
[1:37pm] Crell: Confusing with Symfony I'm more sensitive to.
[1:37pm] Crell: What's your suggestion then?
[1:38pm] katbailey: they are basically just for modifying existing services and adding compiler passes
[1:38pm] katbailey: ContainerFutzer?
[1:38pm] katbailey: j/k
[1:38pm] Crell:
[1:38pm] Crell: $modulename/lib/Drupal/Services.php?
[1:38pm] Crell: Silex calls them Providers (or the closest equivalent).
[1:39pm] katbailey: sure! something along those lines
[1:39pm] Crell: Or rather, ServiceProvider.
Discuss! :-)