The reason historical Prussia found it so difficult to assimilate Germany, aside from its own lack of inherent qualifications and the Austrian Empire—the legitimate leader—watching it like a tiger from the sidelines, was chiefly that Prussia's upper ranks wanted to Prussianize Germany.
Leaving aside the centuries-old conflict between Protestantism and the Catholic Church in North and South Germany, Prussia itself was often regarded as half-Slav, or as Baltic barbarians, the Poles' lackeys.
In short, they were not "German" enough.
There was also the most fundamental contradiction of all: the German had yearned for unity and strength for far too long, yet Prussia's Lesser Germany solution could not bear the weight of those expectations.
And the Prussian government had no choice but to answer those hopes, which was how a malformed monster came into being.
At home, Prussia lacked sufficient appeal; abroad, it could not break the shackles of the great powers.
Bismarck had indeed won three wars, but Prussia and Germany as a whole had always been dancing inside a cage. Yet, to some extent, that cage was also the safe room of the German Second Empire.
What Prussia could not accomplish, the Austrian Empire could now achieve with ease. The Austrian Empire and the House of Habsburg possessed sufficient legitimacy; it could shoulder immense expectations and fulfill them.
Of course, whether Franz would actually do so was another matter. After all, Austria had choices—it did not need to act as Prussia did, as though it had no alternative.
The Austrian Empire's influence was equally formidable, and under Franz's deliberate shaping over the years, it had grown ever stronger. Its power of infiltration was especially terrifying.
By this point, the Austrian Empire's influence in culture, art, and technology had far surpassed that of Prussia in the same period of history.