Although there is another reason:

There are many weird twists of fate in the strange life of Adolf Hitler, but none more odd than this one which took place thirteen years before his birth. Had the eighty‐four‐year‐old wandering miller not made his unexpected reappearance to recognize the paternity of his thirty‐nine‐year‐old son nearly thirty years after the death of the mother, Adolf Hitler would have been born Adolf Schicklgruber.

There may not be much or anything in a name, but I have heard Germans speculate whether Hitler could have become the master of Germany had he been known to the world as Schicklgruber. It has a slightly comic sound as it rolls off the tongue of a South German. Can one imagine the frenzied German masses acclaiming a Schicklgruber with their thunderous “Heils”? “Heil Schicklgruber!”?

Not only was “Heil Hitler!” used as a Wagnerian, paganlike chant by the multitude in the mystic pageantry of the massive [Fascist] rallies, but it became the obligatory form of greeting between Germans during the Third Reich, even on the telephone, where it replaced the conventional “Hello.” “Heil Schicklgruber!”? It is a little difficult to imagine.

(Source.)