Wagner music drama has a psychological dimensions where people sing about their inner thoughts and has a spirit of arias in their music even if Wagner doesn't call them arias.
What Verdi did with Fallstaff was have the vocals follow the natural prosody of speech. Imagine a play where people are talking. However set the speech with a pitch/melody and accompany the play with orchestral music but leave everything else about the actors speaking in the play constant.
Normally it takes longer for people to sing a lyrics then it is to speak it as vocal music has it's own rhythm indepedeent to speech. Verdi attempted to make the rhythm of the singing as natural as possible to real speech.
Also artifice of opera conventions are abandoned to match the script of the play. For example when the soprano enters in, you'll expect an aria as convention to show off the singer, however since this is inconsistent with Shakespear play it doesn't happen in the opera.
Essentially Falstaff is an extended accompanied recitative. However Robert Greenberg's lecture pointed out there is no traditional "tunes" in the opera because the music has to follow the rhythm of speech. Now he says this as a positive thing.
My feelings however is that Falstaff is evidence that Music Drama is a disasterous concept. I have no interest in having music trying to replicate speech as it elevates the story over the music. Tunes are more important to natural speech
Arias are more important than the play
Trying to synthesise them together in a music drama results in unsatisfactory music and unsatisfactory play (as people will find it difficult to even understand the words of opera singers anyway).
Anyway I dislike Otello and Falstaff due to Verdi falling for the music drama gimmick