Per Michigan law...if the lane width permits, you may ride two abreast...but NO MORE than two abreast. You are not to impede normal and reasonable movement of travel (for other vehicles).
There are MANY roads where we live where you can ride 2 or more abreast, simply because they have no traffic on them.
But...anyone riding two abreast on the main roads around here is stupid. While they aren't breaking any laws, they certainly may be lacking in common sense! And yes, you are right...there are many arrogant cyclists who don't understand the "laws of gross tonage" as we refer to it in the Coast Guard!
One thing that motorcyclists SHOULD understand is being visible. That is even more of a problem while riding a bike (no matter what tampon they are advertising on their jersey!). You either ride WAY off to the side (if you have a shoulder to ride on) where all the crap, rocks, dirt, etc. is, or you make yourself a bit more visible by riding closer to the white line. No shoulder (like most of our roads here) means I HAVE to ride in the road. So yes, being seen is a big issue. ANYONE on two wheels should understand this.