Remove creep/minion block
Honestly, it's been in far too many clips/vids, far too many people have made posts about it both with and without evidence and far too many players as a whole complain about it.
If you're going to have it in the game allow players to block minions as well like in DOTA, so that there's a dynamic to it which rewards players for using it correctly, as opposed to hoping it doesn't work, as when it does it's incredibly frustrating, random and uninteractive.
There is no skill to Riot's coding randomly deciding to work in a specific way, same as the fact that this concept as a whole actually counteracts skill both due to its randomness and glitchiness. So no, the argument "But it adds more skill expression to the game" does not and will never apply to the current approach of creep/minion block.
While on the topic, minion pathing is also an issue as well. At this point it feels as if minions just path randomly and inconsistently, making for some very irritating moments, such as and not limited to: minion aggro not fully functioning, cannon creep being lost to a random change in aggro, any minion being lost to a random change in aggro, minions deciding to block you thanks to their unknown pathing.
I don't know how a basic element of this game has been allowed to be this problematic for so long, however, it is certainly time to fix this.
Another extreme example of creeps being buggy would be this (and yes, this still happens even today), and I'll leave this with you guys as my parting gift. Enjoy!
https://www.youtube.com/watch?v=UmKWtVUPagU&feature=youtu.be&t=2m44s