"Ququroon made a great post when Sion was updates that explains why we're moving away from traditional skins -

As you've said, we did create three traditional skins a while back. In the past, we used Traditional skins as a way of allowing players to represent the older merits of a character that we may have glazed over during the creation process. We weren't always confident in what we were shipping, and in extreme cases, necessitated a traditional skin to execute on them in a way they should have been done. This is shown to an extreme in the case of Karma's fans, something that we know we could have done better.

The team has been doing updates for two years or so now, and we have a bit more moxie as to how this whole rodeo goes. We feel we're able to better respect the old, while pushing the bar as hard as we can. We didn't up and change Sion from an undead to a frozen warrior. He's still the same exact fantasy he was before, just executed in a way that he was originally meant to be.

If the team as it is now existed in the past, there are mistakes that we wouldn't have repeated. Karma wouldn't have lacked her fans. Trundle would have better enveloped the 'leper jesus' he was so affectionately known for. Sejuani would have just realized that a bikini wasn't appropriate snow wear. These are things that could be fixed in the future, but we prefer to continue moving forward, as there are still a large amount of characters that need some love coughpoppycoughevecough.

Essentially, we don't feel like traditional skins are the correct answer- the only way to show our love for older content. We still push for constant and continuous improvement in our updates, but we want to do so in a way that best shows respect for older content as a whole package.

Hope this explains the situation a bit better. :3""

There ya go.