That's the mark of a good compromise, isn't it? There are people who have been playing that long that are probably miffed, and there are people that don't have enough essence to get it and those people are miffed.
The truth is, it isn't easy to change these systems, but Riot knows that it's good for the game in the long run. UrfWick is, simply put, a consolation prize. Consolation prizes are never as good as actual prizes, but it's nice to get something for your trouble, you know?
People didn't invest in Runes to get Urfwick. They invested in Runes to play League the way they wanted. Now that the customization is going away, it makes sense to compensate people somehow, but not with a straight IP refund; if Runes are going away, what good is IP? So it's a partial refund with a skin for people with ungodly amounts of IP.
There are a TON of people that don't like this, but it makes sense to me. This is the way the world works sometimes. For progress, sometimes you have to piss people off. There has never been a time in human history, either for real social change or for minor things that almost don't matter on the grand scale (like video games), that this hasn't been true.