It's not optional. A dad who needs asking/telling/nagging to do his fair share is not much of a dad or partner IMHO. The 'men don't notice what needs doing' excuse is just that, an excuse, and saying all men are like that does all the unselfish, fully involved dads a massive disservice.
Yes, many men (and women) have been brought up by mums who did everything and dads who did nothing (often peddled as another reason/excuse for lazy fathering), but they are grown ups now and can make their own choices. A dad that doesn't step up and take responsibility is selfishly choosing an easy life.