You can "complain" all you want, I for one am very grateful for any sleep I am able to get when I am able to get it. I'm pretty sure if you study the sciences and the nature of the human body and what it needs, yes sleep is and has always been necessary.
Was it always gotten in a straight 5-8 hour (or however many you do or don't get) pattern? It is suggested not. I read an article the other day about how in the older times people would go to bed for 3-4 hours, get up for an hour or two, then go back to bed the rest of the night. Typical activities during that time would include reading by candlelight, late night prayers for the religious, having a snack or even physical intimacy among married couples. Then they'd go back to "second sleep" and wake up in the morning.
This was before electricity and in the fall/winter months when it would typically be darker longer. Artificial lighting has changed our habits a lot if this process was true, but typically even they still got about 7-8 hours of sleep a night, they just broke it up more.
Plus, between the two of us, my brain is pretty crazy and I don't think it slows down too much when I'm sleeping...
