If you have the ability to receive alerts when disk space is getting low, then unrestricted growth makes sense.

On the other hand, you don't want one out-of-control database to create problems for other databases on a shared server, so for some environments it makes sense to set a restricted size and monitor file usage carefully.

Personally I receive alerts when a filegroup is getting full, and also when an autogrowth has occurred, so I get plenty of advance warning of potential space problems.