[ojcar]

You have missed my point. If a nation with an (until now) invincible airplane and with air superiority over any potential enemy can develop a new fighter in peace time (more or less, forget Iraq and Afghanistan, because no air to air fighting there), why not Germany could develop new planes?
I think Germans had the edge in jets at that time, but they were early jets, and they had many bugs. They were trying to improve things, because all jets (Allied and Axis) were far from perfect, and they were desperate searching the