The fact you have a 72% winrate is a pretty good sign it's incredibly unbalanced and, as someone who's fought against it, it's incredibly un-fun to play against. For comparison, I can do the most damage or close to the most damage on my team as AP MF with maxing E first, and her E spreads the damage over two seconds. Nasus's E does almost all of the damage MF's E does, immediately on cast, and can potentially double if the enemy stands in it. Not to mention it has double the width, and the only thing you have to sacrifice is your passive lifesteal, maybe some health items, and potentially some Q farm since it can actually be difficult to farm since he can easily use his E to kill an entire wave easily. The rest of your kit (the infinite scaling on Q, the slow, the armour shred, and your ult) is still more or less, equally useful so there's no reason to even build AD other than wanting to pimp smack people with your cane more.
If AP Nasus wasn't broken (and I didnt come here specifically to complain about it and draw attention to it), I'd say your teammates are just yelling at you for going off meta. In which case, ignore them. I dare say even rub it in while it lasts.