I think it also has to do with the Premier league wanting the foreign players. The german league doesn't. They have plenty of them, but they're not glory hunting seeking them out. Look at Bayern Munich, they don't buy "World cup star" or "Next biggest thing" every year, they buy the best GERMAN each year. Bought Gotze instead of going for Bale or someone. That's their mindset, that's how the DFB have made it over there.
Plus most of those teams are owned by GERMANS. Not so in the prem, it's all Sheiks, Russians, and Americans. They would never allow that in Germany. Their biggest team Bayern is owned by a German, same with Borussia. Shalke owned by the club members, Bayer Leverkusen owned by German company, Wolfsburg owned by Volkswagon german company. Premer league big teams man city owned by foreigners, chelsea foreigners, liverpool foreigners, man united foreigners, Arsenal foreigners.
Fix those big issues and I think you'll see a lot more Brits. Just don't be surprised if the league isn't good anymore.