I see now what you mean about the fuses. In their case it is a bit different - the wire connections are saved in the blueprints, but when the actual entities are built, they are auto-disconnected as if you'd placed them yourself, because of the "Automatically disconnect poles of different types" setting.
In the next update, ghost poles/fuses that are placed down as part of a blueprint will not be automatically disconnected when they are revived. This may cause some situations where poles of different types aren't disconnected when they still should be (e.g. connections between blueprint poles and poles/ghosts outside the blueprint won't be automatically disconnected). But I think overall it is an improvement.
When 1.2 comes it will provide better APIs for dealing with ghost pole connections so maybe I'll implement a better solution there.
I'm still working on transformers being blueprintable :)