If I want a skin and I'm giving Riot my money, then they should give me the skin. It's as simple a logic as that. But 4 skins everyday on rotation(excluding the featured bundle), you might have to wait weeks for your favorite skin to come on store. And not like the skins are cheap, they're pretty damn expensive and indirectly need to be paid for to upgrade as well.
I've added some VC to my account waiting for the Reaver Vandal but it's been a month and now I can't even refund the VC for my money.
This is just a sick scam to make you buy skins you wouldn't even want. Honestly the worst system in any game I've played.