* The rune system doesn't influence most champs I play, but I can understand some complaints made by other *
* complaints mainly found on reddit btw, see regular posts there *
The main problem is the fact that 100+ champions are all made too squeeze into a limited pool of options.
Squeezing so many diverse kits into utilising a limited pool of options, will result in a varied set of outcomes. Most will be meh and workable (some runes will work well with them, others won't work that well hence +- = 0), but a few will be particularly OP due too strong synergies (+ + + or even * * *), and in the long run, force these runes that they abuse too be nerfed which will suck for more balanced champs and the OP champions will also end up balanced around that particular OP combination limiting their playstyle options (opposite of what the rune system intended, i.e. more variance in playstyles for each champion).
An alternative that will require a lot more work initially but will likely end up with something easier too balance, is too replace the idea of 'global masteries' and instead give each champion variations of their kit that they can choose from at champ select that will change their playstyles throughout the game.
This would probably be best combo'd with a simple rune system from the past that gives them particular early game stats.
a Tristana that can select a 'kit variation' that gives her some more damage early game.
a Tristana that can select another 'kit variation' that makes her late game become stronger, but ends up missing out on the early game damage.
a Kassadin that will have more mana during his laning phase.
a Kassadin that can choose too have more damage in lane, but end up missing out on easier mana management.
a Leona that can select a 'kit variation' that makes her in lane engages more powerful, but weakens her later on if she gets less kills.
a Leona that can select a 'kit variation' that makes her tankiness scale much better later on in game.
and so on.
Of course, this would require a lot of work, so I was only hoping too add too the discussion.