Notice that Austria and Poland have no AE, even though that peace deal would have given you around 40 base AE and Austria is the Emperor and Poland borders you.
This is because they are your allies. Allying someone you want to conquer later is a very good strategy.
Most of the HRE is OPMs, 2PMs, and 3PMs. They are extremely threatened by any Prince getting larger and have little recourse to stop you, because they can't make a large enough web of alliances to stop you and the Emperor will not protect them, so the bigger you become the drastically more dangerous you become to them. Bohemia has probably rivaled you as well and desires your provinces, in addition to being a Prince Elector who doesn't want you threatening them. The Teutonic Order is naturally worried because you just took a province from them and couldn't defeat you. Denmark straddles the Empire, wants provinces in the Empire, and doesn't want to fight Austria plus a powerful northern Prince to get those provinces.
Without this AE, there would be very little to stop you from simply conquering the whole Empire piece by piece while the other Princes watch in terror as they wait for you to swallow them whole.