The response I gave in some PBE thread to a post from feralpony:
As someone who has discussed and seen the opinion of quite a few people, here's my view on it (some things might not be very clear considering english isn't my first language, also I'm aware it's quite a long read, but I've thought quite a bit about this matter and think changing it does require a large post on my part):
Removing it entirely and trying the rework the items accordingly would destroy years of balance, so it's truly a no go.
People would not enjoy a simple increase in % damage, it would be my favourite option balance wise, but I must admit that the people who say that the disapearance of crit animation (making particals partial would be an insane amount of work) and the high damage spikes from the crits themselves are fun and create excitement (also a fair point).
It could be kept the same as it currently is, but there's gameplay issues with doing this. First it's random (I know it's semi-random in LoL, but random is still random). Randomness in video games itself is not a problem, but for something like a player vs player game such as league where there's snowballing (this is an extremely important variable to take into account) it can cause some very undesirable effects. Seeing as someone get lucky and get a gold lead from it and the next time he faces his enemy he could be unlucky, but due to his newly aquired item lead still win the fight and snowball even further. These sort of situations just feel completely unfair for the victim and not truly deserved for the one who benefits from them.
These notions have lead me to the conclusion that a crit system when the statiscal average is enforced to be the best solution. For those who don't know what this means, it goes as follow, 25% crit = a crit every 4 AA. What about 40 then? Just imagine a bar filling up and every time it reaches or goes past 100 it would be reduced by 100. So if you do 2 AA the third one will push you over 100 and it will be a crit, 1 more AA and you're now at 60 and the next one will crit since it will put you at 100 and so the cycle continues.
And before anyone jumps their horses saying every lane would become governed by a
like passive let me add some more. This counter would be seperate between each individual champion, minions and monsters. The reason for champion counters not being generalized like for the minion and monsters is to be absolutely sure there would no abuse cases. Furthermore (this is the part where Riot programmers would likely cringe a little if it was done, sorry guys) abilities that are some form of on-hit critting AA like

Q would need to have a seperate set of counters for themselves. Yas Q would probably need to prioritize champs when hitting both them and something else (use the closest champ to him as the counter if more than one is hit) and for the tornado whatever is hit first determines if the tornado would be critting or not. Well anyway that was an awfully complex read, sorry about that. Anyway as I mentionned this solution if by far my favourite.
Finally you could also use an hybrid model between % increase and statistical average where you could (for an example at 50% crit) have 1.25x damage multiplier and crit dealing 1.75x (of base dmg not multiplied by the multiplier too). This would obviously complicate things for players, but also make the damage more consistent and crits less extreme. Not really a pretty solution, but can be used if it's for the sake of balance vs "crits are awesome".
Well that was long read now that I look back... Anyhow, if you actually read it all the way through that'd be nice and if you did just acknowledging it through a past even if you're not planning to respond to any of this or/and thought it was garbage, would still be appreciated.