They could work; a test neighborhood willing to try them might be an idea.  When speed humps first were tried in Anchorage they used the rubber types staked into the asphalt and "trialed" for two seasons to ensure neighborhood commitment and acceptance.  They had three major issues - a noisy slap - slap for every car transiting, they had to be pulled in fall and were expensive to place/remove.  They did, however, really test the commitment of a neighborhood to the process!  Eventually the uptake was so consistent and the costs of the rubber humps so high overall that the asphalt ones became the defacto type.