I only want to be noticed for purposes of landing additional work ("branding" as you called it). I'd rather the average reader not notice my work...that's my job, after all.
If I were left out of credits (hasn't happened to me yet) I would ask the publisher/editor/creator about it, but if you guys are working via contracts then just ask that it be included in your contract (that you are credited for your work on the credits page).
I see no reason why a letterer, inker or colorist should be credited on the cover. It's a lot of names and can take away from the overall effect of the cover.
Having said that... if I had Clem Robins, John Workman, Richard Starkings or Todd Klein lettering my books...well, I'd make an exception to the rule.
But tell me...how often do you see any of those guys names on a cover?
Our job is to NOT be noticed. We're the fucking ninjas of the comic world. Colorists are the pirates. We're sworn fucking enemies.