I can imagine you dislike others getting for free what you paid for, but going free to play is also in your own interest. Awesomenauts is a multiplayer game and multiplayer games are more fun when there are more people. Some of the most common complaints we previously got were about matchmaking taking too long, and creating bad matchups in terms of ping and skill. Now that we have more players, the matchmaker can create matches faster and better, making the game more fun for everyone. So you too should benefit from the game being free to play.

Also, note that since you already own the game you get all 20 base characters unlocked right away, including their items, while free to play players will have to grind to get those. And existing players also get a free droppod and an exclusive portrait and emblem.