AA's can be tricky, especially if they are a lot of movement. Heck, Disney has trouble with Kylo Ren and even having the laser cannon effects working (for different reasons on the cannons). The pre-show AA's for Monsters are great but, if they have errors, the entire preshow loses its steam. It's really a no-win situation for Universal. They use screens and are met with sarcastic or scathing comments. They use AA's and have the same thing when the robots break. Maybe Universal needs to upgrade the maintenance or robot technician teams. It's just a lot of moving parts to have all work perfectly.
On the other hand, when guests are paying close to $200/day to visit, they aren't paying to see statues.