Btw, if you are interested in my opinion:
The best would be to merge IP and RP spent in some common "currency" and make you able to spend it on mystery skin chests (what give you a random skin for a champ you own already, including legacy (!) and legendary skins too) and to come up with a similar chest temporary with random champs in them. And everybody could decide how many new champs and/or skins they want.
But to give simple hextech chests isn't a good idea as a single champ shard doesn't worth much and tbh I don't want two more skins for a champ what I will never ever play anyway.
In many cases maybe a simple refund or an option to pick the exact champs and skins you want could work better (in theory I would prefer this system, obviously) but they can't really flood things with IP/RP I think as thinking about the whole community and long long time players, it means a LOT.
This still won't solve the problem of some guys - like one who posted on those forums - who plays since the early seasons, owns every champ and a damn lot of runes what he spent an insane amount of IP on and even hundreds of dollars and he doesn't even want his IP and RP back as he can't spend it on anything but he want the worth of it. Well, so what now?
There was an idea to release some unique skin for these kind of old players, maybe it's a good idea. I don't know, for 150,000 IP+30,000 RP it has to be some very awesome skin :-D