Like you said, many just don't like his current ult (which I love btw, and would hate to have removed), but they also use it as a reason to why he is "weak". So it's both them wanting the old kit for just what it was and for the power you had.
Also, I don't think his ult is only useful at high levels of play. I think it's only really useful in the hands of a skilled player, because it's not easy to use. So in a way, it still is strong at high level of play, but you influence how useful it is, even if you are in gold elo (like me).
One of the reasons it's also strong in soloq is for how you can impact the map early even though you are scaling quite well. The synergy between his E+W and R is really good aswell.
Also, in my experience, pings or the context of the situation are enough to communicate what you want to do:
Ping bot as you and your jgl are about to finish dragon and then ult bot right after its dead for a free gank. Or lategame, when you and your team does dragon, you can ping baron and ult towards it for a free baron (and vice verca). Only to name 2 examples.
So its hard to use macro wise, but not very dependant on team comms or something like that. The uses it has in pro, are the same uses it has in soloq.
Thats the number 1 argument people have against the ult: "It sucks in soloq for us, but is OP in pro so Ryze is kept weak." And I just disagree.
I think Ryze is good in pro mainly for his
I think people often use his current ult as a scapegoat for why he is balanced around pro. Maybe I should make a post about this on the Ryze subreddit to farm downvotes.
If Ryze were to get a stat ult like he used to, his normal combat stats would probably have to be nerfed in order to balance him, right? So I'm not even sure, if people would be happy with his old R back, because he still has to be balanced.