I don't really agree with the runes part being expensive. T2 and T3 runes are literally tiny bit of stats apart. It's completely acceptable to have full rune pages of T2 runes that costed you a couple of games worth of IP and T3 you should only get if you have the IP to dump and want to micromanage the stats they give.
As far as the rune pages go, yea, they are still expensive.
As far as the "i need IP to buy champions" argument, it's is still a moot point.
You'll never have enough IP to purchase everything you can at once. It's always about "what do i need now and what will i get next" thing. Every new champion is just another item in the shop and assume that you'll need about 6300 IP to advance a mastery level - that's one 6300 IP champion. It shouldn't be 1 IP nor it should be 10k IP. It's in a reasonable range because the baseline is one new champion purchase.
And as far as the price to advance to lvl 6 and 7 goes - there has to be a price.
If not essence, they it'd probably be 2 S- or higher + S+ token or 3 S or higher + 1 S+ token.
S+ is incredibly hard to get, especially when you don't know the criteria. It varies across the roles, champions and probably on a daily basis. Some lucky people would have gotten their Mastery levels but for the majority, it would have been an extremely hard task to complete, inevitably finding their way on the boards and reddit, complaining how the grading system needs revision because "it's too hard".
Lvl 6 & 7 Mastery isn't something easy to get nor should you strive to acquire for every champion you play. It's something you should be getting on your few most played (favorite) champions.
I don't find the Mastery system problematic and i also haven't received any champion shards from the loot (thank god because i'd rather have skins). I am fine with buying mystery champion shards with IP. I don't own all the champions, i currently have 20 and i certainly don't have a backlog of IP i need to get rid of either.
In all intensive purposes, i am the average player everyone keeps mentioning in these arguments and how hard it would be for people like myself "to get enough IP" and that simply is not true. Everything in LoL shop (that is gameplay related) costs you IP already, adding one more thing to it won't suddenly put me in such a position to never have enough IP to buy a champion ever again.
Thanks for worrying about me but i can speak for myself. I am completely fine with how the system works and i can also understand that some people won't like it as well.
It's just a matter of an opinion.