It is required and required for any reporting functionality. With SQL 2008 and 2012 there is the option to auto configure Reporting Services when it gets installed and most times this is enough to make it work properly. Again I think it is more the instances where someone doesn't let the installer configure it or tries to configure it themselves ( and does it incorrectly) is where you run into problems. Usually of you can hit both the /reports and /reportserver URLs everything should be good.
If you are walking into an environment where SQL and SSRS is going to be installed already,usually a note in the scope of work indicating time spent troubleshooting problems in this area is out of scope.