1,000 seems excessive to me. I've been playing since season 1 and I have somewhere between 2k-3k games on my account. However, I could see something like a combined time and # of games played requirement.
I'm not against the idea. I've never been banned at all, but I do like the idea of account redemption for those who reform, I just see a lot of difficulties with implementing it. I'm totally for it, but I'm not sure that RIOT is going to be convinced to put something like that in when, in reality, probably under 1% of banned players would ever reform to the point of getting their accounts back.
My thought is, from RIOTs point of view it looks like: We put this in, it rewards the 1% of the 10% of our players who are banned and then truly reform, but to reward that .001% of our player base we're going to have to put up with 100% of those banned players who get banned and whine about getting their accounts back but don't deserve it. Plus those .001% of players now have a new account with over 500 games played on it, so why do they desperately need the old one anyway?
Witness the DarkLarvitar guy above who has had whopping 10 or 11s account banned!! and still thinks he deserves to get them back. I like the idea, but it'd be a headache for RIOT to deal with and I doubt you'd convince them the upside was worth it.
I think the biggest question is: Can you convince RIOT that putting a system like this in place would cause a significant number of players to truly reform who would NOT have reformed otherwise? If the answer is no, then, as much as I may agree with you that the idea is a nice one, it isn't going to happen.