Our first E53 did not have running boards. Our second one did. Would never consider buying one that did not have running boards for long term ownership again after that. Much prefer the looks of them and think they only add to the sportiness.
As you say, it's subjective. Even the wife's E70 had to have running boards (she likes them) and they get your pants dirty anytime you get out of the truck unless you are careful. They have their upsides and downs.
^And yes, they really help when cleaning the roof of the truck. I never liked having to open the doors, take my shoes off or flip-flops to step on the inside door sill to wash the roof.
Wait a second... I have pics of my old truck without running boards, and with running boards (+flares). Spacers were added after this picture though to push the wheels out to meet the flares.
