Champions need to have AP scaling even if they are expected to build AD and vice versa
One of the greatest fun I ever had on Lol is to experiment new builds that most people would not ever consider building. The most fun I ever had was playing AP Miss Fortune(before gutting her E), AP Shaco(before gutting his E into AD), AP (Pre-Reworked) KhaZix(Before ADfy his passive, thanks to the AP scaling on some of the champions. However, most of the champions being released/reworked recently has been limited to one scaling and this renders half of the items being totally unusable on them. For example, reworked Urgot only has AD scaling, reworked Mord only has AP scaling, Pyke only has AD scaling, reworked Aatrox lost his AP scaling on his ultimate, reworked Kha's lost AP scaling on passive.
I do not think it is a good trend to keep making champions one way scalable. It reduces the fun of trying out new builds. It forces you to build in a certain direction and it feels like the game designer is telling me what to do and build, instead of having the authority of deciding my own builds and play style.