Several times has quasi connectivity ruined my day (and I'm guessing many others') when building a machine. I understand that sometimes it helps and it is really interesting, but I think we can all agree a way to stop it in some cases would be nice. I suggest glass since transparent blocks do not transmit power downwards, and as such it would be intuitive that they stop quasi connectivity (which consists of power being ""anomalously"" transmitted downwards to those three blocks).
However, if you do want to use the bug feature, this change should not hinder it at all since any other blocks, including air, would still behave as they do now.
If there is a workaround which doesn't increase size of the device, I don't know about it. I feel many people starting with redstone are especially frustrated by this, and I think making redstone more friendly while not reducing challenge and originality is a purpose that stands by itself.