Have to disagree to a point. There can be a certain level of attraction, I've been in that situation, but if it's never going to happen and as a person you want them in your life regardless because you value the friendship it's a different thing. If years go by and you want to bang her 24/7, that's...unusual.
Value of a relationship - okay up to a point. Every friendship, male or female is important - they are supposed to make your life more better/interesting as you can make theirs. I am not discounting that you can make good friends with females - I am good friends with an obese woman in her late forties who has managed various pool clubs in the town.( It helps that she is damn good pool player).
As your get older you lose touch with many bygone female friends - (never have had female work colleagues) the last circle probably from the 'the clubbing scene' from fifteen years back - at a reunion, you do notice the men manage to make it, a little heavier, some bald, some a little worse for wear but the females are generally absent. Who knows why? They get married/have kids but so do men. But there you are. Perhaps it is the drugs/drinks.
So the female friends you tend to keep and see regularly at an older age are those that in my case seem to be the still single/on-off boyfriends/divorcees/changing boyfriends types and plus still sorta sexually attractive that enabled you to notice her personality quickly in the first place but now twenty years down the road the friendship comes to the fore.
But are you saying that if said still attractive friend ever in a 'moment' placed her hands on your knob and worked it - would you still say no? Suppose that you have a million of these 'moments' would the answer be no in every case?
So it is not simply a case of years going by and thinking of banging her 24/7, but in a year the question might rise once or twice. What would she be like in the facet you know nothing about?
Whilst drunk a few female friends have indeed 'propositioned' in form a sentence but I have always managed to pretend I have not heard and up till now, none of the few ever repeated it again.