Regulations regarding the use of motorised ( electric or ICE..makes no difference) vehicles varies from country to country. The ONLY place you can use motorised vehicles in the UK are on public roads or on private land with the land owners permission. I know that differs in different countries.
Obviously the entire derestriction debate is about motor assisted speed............note that there is no absolute speed restriction for bicycles. The regulations regarding pedelecs included a specific maximum motor assisted and maximum nominal power of the motor primarilly because there was a need to fit pedelecs into a category below that of mopeds with a clear margin. What they did was to include pedelecs in the bicycle category.
As far as the EU regulations ( and for reasons of history the UK also) were concerned, to allow higher speeds and motor power would make the Pedelec category too close to that of the moped, and thus mean adding a plethora of additional legal requirements.............registration, tax, insurance, manufacturer type approval, helmets, lights, horn, testing, more age limits..etc.
Motor vehicle categories and legal requirements vary in different territories which may allow for more flexibility but as far as the UK is concerned at least, a more comprehensive revision of Road Transport Laws will be needed before any consideration can be given to increasing motor assisted speeds for pedelecs. Increasing the speed of any motorised vehicle is an unlikely cause for any MP to champion merely to win approval from a small niche of the voting public!!