Same thing with my Sennheiser bluetooth headphones. It may seem like no one will want to use them while connected to a wire, but sometimes having awkwardly-wired headphones is better than having no working headphones at all.
If they're anything like my last sennheiser headphones, they will let you use the 2.5mm to 3.5mm adapter while the battery is depleted but then you need to carry two wires.