The number of reports I've heard of on here from cyclists that almost get hit despite rear lights tend to indicate that blinkies are absolutely necessary.
Additionally, let's say it annoyed you, but you're an average or above motorist from an attention standpoint. We need something to get the attention of the least attentive drivers. That's a blinkie, for sure.
And I think the general response to "hey, there's a bright blinking light in my face" is supposed to be getting away from the light. Which would involve not tailgaiting the guy, passing close, etc.
I use just a Superflash, which is pretty bright for a small blinkie, but I've gotten no screams of complaint from motorists. I have gotten a single complaint from a driver who didn't like getting a Dinotte headlight in the face, but oh well.