Hextech crates are a complete joke

Excluding the Project crates and any other free crates that may have been given out, I've acquired and opened 18 crates from getting S-ranks. Of those 18 crates, 22% of my "rewards" have been skins for champions that I actually own (that's 4 out of 18).

For champs that I do own, I've received: Death Blossom Kha'Zix Midnight Ahri Rumble in the Jungle Resistance Caitlyn

For champs that I don't own, I've received (to name a few): Warring Kingdoms Tryndamere Demonblade Tryndamere Sultan Tryndamere General Wukong Lord Mordekaiser King of Spades Morderkaiser Bioforge Darius Commando Galio Mistletoe LeBlanc

Someone please tell me why the hell this system is so awful and why I keep getting so many skins for the same fucking champs that I don't own (Trynd and Morde), even the rerolls give me the same garbage. The rest have all been champion shards, which are literally worthless to me.

I get it, you people need to make money somehow, so you cripple this free content system with bullshit. But, can I at least unlock content for shit that I fucking own? Even just a 50% chance, something that's actually worth a damn. As it stands, going through the trouble of getting an S rank and opening a crate is like going through army boot camp then having someone smash your nuts with a sledgehammer after you finish. Why should I even bother?