Notify only when a new revision is created

No, Subscriptions doesn't make that difference.

If we wanted to do this, we'd probably have to do it by content type, which would require another complicated configuration option. We already have too many of those...

I let this stand to see whether there was general interest, but there isn't.

You should be able to implement hook_subscriptions_queue(), inspect the node, and set it to NULL if you don't want it queued. Code-wise this should be easy to do if that's what you want to have, i just don't see a good way to make this configurable for general use.