I think keystones in general should be removed, but other runes are fine if balanced right.
The idea of changing your playstyle to conform to a rune is a bit much, and giving players less freedom
But other runes tend to be so minor that you can't really play around them. Instead, they strengthen certain aspects of playstyles. For example, in an ideal setting, Ahri could go sudden impact, or she could go taste of blood, both of them being very good in that she can either play a sustain-y mage in lane, or an assassin mid to late game.
I used to believe runes and passive effects that you opt into should always be flashy to some degree, otherwise you just work them into base stats or have it picked automatically without wasting any 'points' or 'slots', but now I believe that all other examples of passive effects have just been terrible and skewed my perception. In your typical WoW like MMORPG you're going to take that 3% damage to orange female dancers because it lets you get that next ability which is an active that sends 9000 daggers in a cone to swarm at an enemy. Or because people crunched the numbers and it's the best in a PvE game where the enemy doesn't really do anything unexpected. What hasn't changed though is my hate for skill trees. Please for the love of god just remove those.
What matters is, you know when it's strong and you know when you're in a situation where that rune matters most (late game, early game, long trades, drawn out attrition teamfight), and that it to some degree does make you noticeably better, not enough that you try to throw yourself into these situations, but just enough that you acknowledge that as a player you want to cover a weakness or double down on a strength so that when that time comes you have an ace that'll make you just that tiny bit better.
Runes that I think should be kept disregarding numbers entirely:
- Legend runes
- Coup de grace, cut down (minus AP/AD on kill), last stand
- Dark harvest on towers, predator movespeed boost
- cheap shot, taste of blood, sudden impact
- zombie ward, ghost poro
- hunter runes convert into legend runes
- absolute focus
- scorch, gathering storm, waterwalking
- grasp damage
- demolish
- overgrowth (but non linear), revitalize
- hextech contraption
- future's market
- approach velocity
everything else remove ty.