Looking around these forums and elsewhere, it seems clear that bicyclists generally believe that motorists become irate when they have to slow down, and it is due to this inherent impatience that bicyclists are often scorned.
I don't think that's actually true.
I am a new bicyclist myself. I think I have a different perspective on it than someone who has been riding a bicycle all of their life.
I drive a Corvette. I drive quite fast at times. I don't like to slow down. And before I started bicycling myself recently, I had a pretty dim view of bicyclists riding on the street.
It wasn't because I'd have to slow down for them. It was because I thought they were doing something they shouldn't be doing _and_ inconveniencing me while they were at it. I don't like to slow down in my Corvette, but I don't mind it when it is justified. It bothers me only when I feel that it isn't justified.
I've noticed, for example, that motorists don't seem to get upset at stopping for pedestrians in a cross walk. I can't think of when I've ever seen a motorist yell at a pedestrian to get off the street in this sort of circumstance.
Yet if I inconvenience a motorist even slightly while taking the lane in my bicycle, they're liable to be irritated and honk their horn or yell. Bicyclists clearly get treated very differently. That much is obvious to me already.
I believe the real cause is that most motorists (myself included) only ever used bicycles as children before they got a car. Parents teach their children to ride bicycles on the sidewalks as if they were pedestrians. So whatever the law actually says, most motorists know that you aren't supposed to ride a bicycle in the street where the cars go.
They think that because they were raised to think that. They probably even got spanked if they did otherwise.
And the state does very little to teach them what the law actually is when they get their licenses.
I didn't even know taking the lane was legal myself until a few days ago.
Motorists get irate at bicyclists primarily because they believe bicyclists aren't supposed to be riding in the street where the cars are at all. Forcing a motorist to slow down amplifies that irritation, but it's not actually the root cause.
I can see where this is a difficult situation that's hard to untangle. Even if a motorist is told the actual law, it conflicts with how they were raised. So the typical reaction is going to be skepticism rather than acceptance. They'll think it's one of those weird outdated laws everybody ignores.
So how do you fix that? Should parents have their children ride in the street in vehicular lanes so they can be raised to ride bicycles correctly according to the law? A 12 year old on a 35mph street surrounded by SUVs? Not very likely!
I don't know what the answer is. But I think it's a positive step to understand what is actually going on rather than reflecting anger back at motorists and blaming it on them. It's not really their fault. The situation is the result of a complex issue, not a character flaw of the motorist (or the bicyclist).
I hope for more progress on these sharing the road issues because I'm loving riding my bike.