Hitler was actually a fine orator.

1) He understood what the masses wanted: bread and pride. He essentially promised to "make Germany great, like it once was", to modify a campaign slogan of RWR.

2) His speeches were constructed to bring people along with mood, language and tempo.

He would begin with longer, more complicated expressions, and deliver the words more quietly [this latter might have been more a pre-Putsch delivery; Speer refers to it in his Erinnerungen.].

As he talked, the phrases got shorter / less complicated, the tempo increased, and his own demeanor kept pace with the tempo.

He ended up bring people from where they were to where he wanted them to be.

The results of his speeches are written in unspeakable cruelties and horrors, hatreds, confiscations, and the blood of persons of all ages killed in many ways, both near to far from München and Berlin. His speeches helped to destroy Germany, redraw maps, create a Communist empire of occupiers who blighted a vast region of Europe for 44 years, create an American empire, and reshape the world.

So I'd say his speeches were effective.

An evil person can be a good orator
Not all evil people are good orator

A person can be banal
A banal person can be a good person

A person can be racist
That same person can be a good orator

Hitler was a "good orator", because his audience was extremely receptive, and this allowed him to take control and cause evil.

seems you have an obsession with the word banal, a word coined by Hannah Arendt at Adolf Eichmann's trail, try not to get carried away

Improper word.
Be thankful that such types of people are not trite or common place.