I was a Ryze main during S5 and S6, but when he got reworked in mid S6 i just stopped playing him. There are a lot of reasons that now I'm going to explain:
1- **The 3D model**: why is Ryze so thin? Why does he no longer carry the spellbook with him?
2- The splash art, the quotes and more: just why. He was fine.
3- The gameplay: Let's talk for a while: I have to admit that Ryze was way too OP when he came out. The permaroot was very annoying to deal with. But when you guys, Riot, nerfed his passive so he could only reset 5 spells, his winrate dropped and he was just a fair champion. I don't understand why you guys had to rework him again. Because now we have a champion that is OP in the competitve play, due to his ultimate, wave clear and poke, but almost useless in SoloQ.
I really think that what would have made Ryze a true balanced champion would have been the following: His passive should have had some sort of CD. Because he reached what you called "powerspikes" too often.
I've also heard that you are planning to change his W, so it wouldn't be as effective as it is right now. I think it's a good idea, but you should introduce a mechanic that involved reseting this W. Ryze would be much more interesting.
And last but not least, just one last advice: As I see it, you should focus on who made you what you are, and this is the community, not the pro players.
Feel free to comment, flame or whatever you want!