I take your point, Gostav, but it is much more that the majority of people - and that goes for enthusiasts too - simply aten't interested in EMUs. Witness the Electric Railway Museum in Coventry which had a go and (for a long time before it was evicted from its site and the collection dispersed) simply couldn't attract enough public interest for it to look like anything much more than a linear-ish scrapyard (one for you, Paul).
The complete 4SUB arrived in reasonable condition, but there was never enough money coming in to keep the collection of vehicles in reasonable condition and water ingress did the rest. Hopefully it now has a brighter future, but if you see the achingly slow progress that is being made by the tiny group working out in the open on the single 4DD vehicle at Sellinge, I'm not holding my breath. Restoring a full EMU is pretty much a losing battle unless you have a bunch of very keen, hands-on people with deep pockets or can contract work out, like with the Swanage 4TC (not technically an EMU, but you know what I mean)
Full EMUs take a lot of money and work to maintain and also a lot of siding space... for something that the majority of the public isn't interested in. Hauled coaching stock is a lot more flexible and, with the vast majority of UK heritage railways using vacuum brake, air-braked EMUs also aren't attractive as hauled stock to most lines, whose majority of customers want to 'ride on a steam train'.
However, this has now gone way off topic. Back to expansion plans...