Token support in root folder

content/images/[current-date:custom:Y]/[current-date:custom:m]/[current-date:custom:d]

This looks very project specific and thus more like something that should be done outside the code e.g. via a cronjob and drush:
drush -vset media_root_folder `date +%Y`/`date +%m`/`date +%d`

Further this adjustment would raise a lot of questions e.g. how to access the "old" media root, what happens to subfolders, is a garbage collector necessary and so on. Again this sounds very project / solution specific - thus I don't think it should be part of the MBP code base. (The only thing I could imagine is a dedicated function to get the path to the root folder that fires an alter hook)