I'm not opposed at all, I just doubt that the motorists that have no clue what it's about feels like they are being accused of anything, as the OP suggests.
I think they are about as silly as the roadside crosses, since they don't give any context as to what circumstances occured, but if they make someone feel better for having done something, that's fine by me. Maybe at some point motorists will come to recognize them, although I would think the use of an already recognized memorial might be more effective, but I doubt that even recognition would lead to safer driving in regards to cyclists. Most drivers don't understand how they are supposed to interact with cyclists on the road, and I don't see how such a memorial will teach them.
__________________
Tom
"It hurts so good..."