They will be offering trailers next with banks of batteries for hundreds of miles travel! I have two batteries and carry the spare in a back pack when required, its no great deal to switch them over, I guess its the designer look of my Mercedes Smart eBike I wouldn't like spoilt as it gives me great pleasure every time I mount it, having a load of batteries on it would make it look like a working mans cycle.
It may suit some working class people though who don't have access to proper private transport, but unless sealed would leave the electrics vulnerable if you only wanted to go out on one battery, plus it will start to look a bit utilitarian.