I would suggest you to submit a issue on Github as well, and see what they say about it: GitHub · Where software is built
From my understanding the 2mm retraction is necessary for prevent dripping/oozing from long travel moves. After a long travel deretraction of 2mm might be too much. Without a prime tower you would not want such a long retraction, I think they need to turn it down a bit. With a prime tower, if you add a deretraction here, chances are for some filaments you would have lots of build up:
These blobs and build ups might cause the prime tower to fail and get knocked over.
https://wiki.bambulab.com/en/software/bambu-studio/parameter/prime-tower
Better have a detailed read here, it explains a lot of concepts behind the current design of prime tower.