Nice to have...
...but if the gigs you're trying to get don't require one, then you won't need one!
Some places DO want to hear ya, others don't give a damn... if the deal you cut is "for the door", they may be less picky about wanting to hear ya first.... on the other hand, there are no rules about it........
You're better off having one, that way, it's there if you need it!
Bruce