I disagree with this statement. To be qualified an "ass," in my opinion, would mean Bottom would have to be stupid, which he is not. Bottom is missing elements in his life that have prevented him from being truly happy, in my opinion; therefore, he seeks attention which equates to love for him. He may seem foolish, but his motives are fueled by the need to be desired, wanted, and appreciated. Without Bottom, in addition, the rest of the group is simply lost. When Bottom disappears for the time he is with Titania, the group worries about him and knows they simply cannot do the play without him.
Nick Bottom the weaver and his friends make up the farcical element in "A Mid summer Night's Dream." Their clowning and malapropisms are meant to generate laughter spontaneously in the audience especially amongst the 'groundlings.' For instance in ActIII sc.1 Quince remarks," Bottom!... thou art/translated."
Initially, It seems as though Bottom is a fool who is over enthusiastic in wanting to play the roles of Pyramus, Thisby and the lion simultaneously. But his intelligent grasp and sound knowledge of all matters theatrical can be seen during the rehearsal in ActIII sc.1 when he solves all the technical problems concerning the actual staging of the play-how to avoid showing the killing on the stage; representing the lion, the moon and the wall on the stage. In ActIV sc.2 Flute remarks that in the whole of Athens no one else can play the role of Pyramus better than Bottom,"he hath simply the best wit (intelligence) of any handicraft/man in Athens."
In Act V sc.1 during the actual performance of the play Hippolyta remarks,"this is the silliest stuff ever I heard." Theseus at once defends Bottom and company by replying,"the best in this kind are shadows, and the worst/are no worse, if imagination amend them."
So, although Puck transforms Bottom into an ass it is clear that basically he is an intelligent person after all and we have to view his character sympathetically just as Theseus was sympathetic towards his performance.