That doesn't mean its easier. The actual renovations necessary can vary widely even in homes considered low ratings, which is often due to something as simple as use of electric heating. The concern I would have is that we are railroading in technologies which will appear just as dated in 20 years time as oil fired central heating is now. What we should be focusing on is creating buildings that are built to last and modifiable, which is why timber framing is so popular elsewhere - if your beams rot on your 19th century Fachwerk home in Franconia, you replace the beam with an appropriate load bearing beam of similar type and take it from there.
What I do find strange here is our lack of appropriate use of basements, ground floor space and rooms under gable roofs, like I've seen in Germany, Luxembourg and Switzerland.