There is a 25 song limit in the bulk editor because of how long some actions take to process.
For example, uploading images can take some time. More songs being selected means that more uploads would occur, which in turn means that the processing of these images would take a very long time.
We have limited the amount of songs that can be opened in the bulk editor to 25 so that you're not stuck on this page for too long.
Have any feedback or suggestions regarding the bulk editor? Please feel free to email firstname.lastname@example.org anytime!