In part... the other part was that the Amiga market was shrinking rapidly so they had to move forward. 
That and the Amiga name was heavily identified with the failure of Commodore and the bad taste it left in everyones mouth.
Other PC makers we struggling at the time yet were allowed to go into Chapter 11 (or close to it) and restructure...
Coming out with spanish "Amiga" sounding brand names like... Performa, Aptiva, Presario etc...