It's brand re-inforcement. Whatever you do, once you create your brand (or it creates you) you must not deviate from it. So keep the essence of it simple and easy to transfer or duplicate.
Notice how the examples above are not logos or even appear to have been created by a designer.
As a designer, and as a person who approaches life from this perspective, is it odd that I think design in the material and aesthetic sense does not play a role in the key development story-telling and foundation of the brand?
Brand is story, really. No story, no brand. Only the big guys can create a brand out of thin air, then create a following to buy it. Even then they often flop. The authentic brands (and you don't even want to attempt a brand if you don't have something real) rise up out of the chaff, the essence revealed: it was there all along. Or sometimes the story is contrived, but the brand strategy behind it is real.
Let's look at Mr Roth. Yes, the justification for his destructive rampages upon discovering the banned confection is as legendary as the rampages themselves--he was testing the rigour of the crew by burying the diva-worthy rider deep in a technical contract. Stories of the singer trashing backstage rooms and forfeiting sold-out shows struck fear into the hearts of stadiums and promotors everywhere. They served another purpose--they made Roth look like a singular loose cannon whose antics both broke new ground and grew into legends. The David Lee Roth brand stuck. Really, did Sammy Hagar ever fill those paint-spattered shoes?
It could be your laugh, your car, your quirky love of the perfect cup of tea, or those things could just be supporting roles to your real brand, maybe your insistence that the products you make must be made locally, or the service you offer must be accompanied by a follow up quality call. Find something you do differently and better than the rest, and live it-then fiercely protect it!--but more on that on another post.
So yes, logo, ID, company colours, ALLLLL those things are critical and the philosophy of your company/venture/persona need to be consistent, but it is the most unique thing about YOU and where you came from that is your brand. You might just need some help boiling down the essence of what that is. I might even consider a creative writer before a designer if you have to hire only one consultant. Hmmmmmm.....