Supposedly because they plan to give a lot more orange essence for free this year.
...at the current rate though it seems like they are taking previously free/already built things and making them cost orange essence though. The Deathsworn event was meant to require Orange Essence for the ward, and the project skin shard requires spending Orange Essence to actually make the skin. So you technically get more Orange Essence (as a free/low spending player: if you bought boxes you're screwed), but it comes at the cost of not getting any of the cool event things now.