Operation is easier if you can select data assets and data connections that have business terms assigned to them from the default catalog and push them to individual data catalogs.
Even if you automatically assign a term in data discovery, it reflects only the default catalog.
I think that it is an operational burden for each data catalog administrator to make data connections, add data assets, and assign business terms.
By allowing assets already registered in the default catalog to be pushed to individual data catalogs, you don't have to add data connections, data assets, and business terms to each data catalog.
NOTICE TO EU RESIDENTS: per EU Data Protection Policy, if you wish to remove your personal information from the IBM ideas portal, please login to the ideas portal using your previously registered information then change your email to "email@example.com" and first name to "anonymous" and last name to "anonymous". This will ensure that IBM will not send any emails to you about all idea submissions