I disagree with the direction of the nerfs, since it's Ahri's Q waveclear that gives her strong roaming power and a lot of builds can easily get away without building Morellonomicon. She should be receiving higher mana costs on her Q instead.
But even if we look into the current nerfs, these nerfs are just really bizarre and make her far worse at fulfilling her role as a burst mage even if you do land charm.
W AP ratio decreased from 0.4 to 0.3 means that a single target W only as an AP ratio of 0.5, compared to 0.666 live. That's a net loss of 0.166 AP.
R loses 0.05 AP per cast, making it a total of 0.15 AP.
E is buffed by 0.1 AP.
In other words, Ahri loses a total of 0.316 AP from her W and R and only gains 0.1 AP on her charm as compensation. Even if she does land her skillshots, she still does less damage than before (Riot didn't you say that you want to reward Ahri for landing skillshots and punishing her for relying on no skill abilities???). Furthermore, considering that E is on a significantly higher cooldown than W, the damage loss is enormous in a teamfight.
These nerfs do not make sense at all unless you buff charm even more (maybe give it lower cooldowns at higher ranks so it's actually worth maxing second?).
Furthermore, her Q is completely untouched, meaning the oppressive builds that don't build mana regen and shove hard are still going to do well. The reduction of AP ratios will push her even further towards Gunblade/Lich Bane/Protobelt as AP has become a worse source of damage for her. Riot, are you really sure you want to embrace this playstyle? You've been saying for years that you want to make Ahri more into a kite mage, but these nerfs are pushing her towards this no mana regen/assassin playstyle even more.
Please reconsider the direction you are taking for this champion and don't force her into this horrible playstyle even further.