Though i will admit, that League of legends does have cost issues, its rune issue is technically resolved greatly by allowing tier 2 runes to be 1 ip cost. Which sadly is going to have that slightly weaker niche and lack of variety. BUT it still allows the ability for new players to at least not be completely nekkid in runes and could have a glaring stat gap as they progress in levels.
Some champions 'should' probably be bumped down in terms of cost, such as maybe 1500 less for a good sum of the 6300 champions, some 4800s to 3150 and a few 3150 champions to the 1800ish tier. Since keeping a huge variety of them, even though they've been out for over half a year or even longer, not getting a value drop makes it less reasonable to obtain champions that look awesome, which also a good deal of the 'meta' or constant power house champions in random matches tend to be a good number of these 6300 cost champions.
As for the 131 champion roster, really its more of a matter they need to address the huge niche of champion grabs that clog up the pick decisions due to kits that will utterly stomp most standard champions. Though i've seen plenty of champions rotate in and out on terms of viability, some of the ones i never see that ever lost its snowball power or plain annoying tankieness is Vlad, Swain, Yasuo and Morganna, in addition to champions who always have huge blast or screw with you presence like Zed, Le'Blanc, Lux, Teemo, Xin Zhao and Volibear. Though some other champions exist currently that are power houses especially in current meta (cough Darius, Illaoi, Nautlius, Hecarim cough) of plain playing massacre tank types even when their role is suppose to be 'beefie and damagie' but should NOT be able to be beefie as tanks 'should' ideally be.
The match making setup if i recall 'does' prevent you to an extent on not getting paired up against a full team of players already at level 30, but it would be nice if they in 'Solo Queue mode' that has been cried for alot. They could even further this by Solo queue also having a default setting when your a champion below certian level thresholds so you are only paired with and against other champions within that threshold to give a better experience for those players since mastery effects and stacked runes or tier 3 runes will not be as possible on those other players, meaning you have a fair advantage for a good while.
Plus obviously for Solo Queue the benefits are huge for many of the people suffering constantly against being matched up with and against large teams that make no attempt communicating with you or the enemy team is so coordinated, it makes you think they are playing rank mode instead.
-1. Force out grouping players and get players to develop skills in interacting with random team mates to be able to coordinate for working together then complaining if someone puts focus on keeping the lanes from getting pushed up on your team sides, and then soon as you join them, a opponent will sneak in or TP in on those side lanes, break a turret like crazy, then run away.
-2. Allow players to interact more with each other and create better opportunities to meet people and maybe add eachother to your friend lists and then team up in groups for 'dynamic 'regular' queue matches'.
-3. Eliminate the presence of what is likely why grouped players are crying for all the time and a good number of players who solo queue up would suffer further from, the presence of a voice chat system. Its already likely plenty of grouped players are running a voice chat program while playing so they can be even more insanely coordinated then typing in chat. Which ends up as a major dis advantage for the new'er players who would get curb stomped all the time due to constant presence of a variety of teams which want to be toxic and usually ends up making players want to leave the game instead of dealing with toxic players who pretend to be pro league epics, but likely got boosted, run with team mates all the time and never actually proved their own skills in 'solo queue matches' and play champions which are overpowered and soon as they get under powered by heavy nerfing, they just throw them away like used toliet paper and play the next over powered champion at the moment.
League of legends needs alot of things, from champion balancing, itemization balancing, mastery balancing, etc. But it still at least proves to be a fun game when your not stuck in a constant 'your team doesnt have access to the meta pick champions and the opponent is loaded with 2 or more of them being meta champions and just effectively snowballs you to death, even when you ban all the 'most powerful champions' and yet still more exist that are just as ridiculous.
