Nasus only usually can reach tanks. The % shred is to make sure his damage matters, He is a late game hyper carry melee, and his Q CD, only during ults which is 15 seconds of power by the way in melee range, is to allow him to do relevant damage against armor stacking high health front lines. It makes sure the tanks can't just ignore him and go for the back line. Before even at 800 stacks against full armor tanks with 4000+ HP would maybe do 200-300 damage.
Nasus needed this change and his win rate is only in relation to his mains. His pick rate is around 5% which is the approx player base that plays him regularly. There are plenty of other champion that do his level of damage while being mobile while having decent early games through late. Olaf, Fiora, Jax, Riven and Pantheon to name a few. Pantheon, even late game hold above a 50% win rate for his absurd 54% win rate early to a 52% win rate late.
Stop bitching about a champion with an atrocious early game who was in desperate need of some love.