Not that you don't already have your answer, but I'll chime in as well.
The standard "let it rest" concept has to do with, for the most part, purchasing cigars from vendors. Most vendors keep their cigars a bit on the "wet" side. Packaging them up and shipping them puts them in a non-ideal environment (i.e. not a humidor) where the temperatures are not constant and humidity can fluctuate. So smoking cigars immediately upon receiving them can result in burn issues because of humidity as well as taste issues. Allowing cigars to rest in YOUR humidor for an extended time assures that the cigars are acclimated to YOUR preferred humidity. As has been mentioned, many prefer something around 65% instead of the standard 70%. It can take time for cigars to divest that extra humidity, especially an entire, sealed box. Certainly cigars can be smoked Right Off The Truck (ROTT), so to speak, you just risk a bad impression of what could be an amazing cigar. Of course, sometimes this is good as it makes you relegate the box to the back of the humidor for even longer. :thumbsup:
Now, if you are talking cigars that are coming from a Brother in a trade or something along those lines, things can change. I've recently received some singles from other Brothers via trades and PIFs (Pay it Forward) and the transit time was so minimal (2 days) that I only allowed the cigars to sit for 1-2 days before lighting one up. And it was fantastic. But I knew the conditions the cigars were kept in and knew I would appreciate them based on those conditions.
So, do you HAVE to rest them for that long? No. Just keep in mind that if the cigar isn't great, it may need some more time to adjust.