I'd like to purchase spine but wonder if anyone could explain to me why I might want to get the professional version.
Here's a list of what's missing in "spine essential":
- Meshes
- Free-Form Deformation
- Weighted Meshes
- Clipping
- IK Constraints
- Transform Constraints
- Path Constraints
What do you think would I miss most likely if anything when creating spine animations for a game like i.e. a platformer?
The biggest / most used thing an "average" user would probably miss would be FFD - essentially stretch and squash which is an easy way to help give a bit of life to your animations without having to be an expert animator.
IK helps with certain kinds of animations but isn't essential - think of something like pinning a characters feet to the floor and being able to drag him by his arms and have the rest of the skeleton move / react accordingly rather than having to move the skeleton bones manually into position.
Clipping isn't supported by GMS due to how old the Spine runtime is, and the stuff like Meshes, Weighted Meshes and the Constraint tools are a little more advanced and whilst useful, probably aren't going to be used by someone just getting into using the program for some basic game animations.
I think if you upgrade to Pro afterwards then the cost of Essentials is deducted from the price, so it's not like you will lose any money by testing the water with Essentials first and seeing what you think.
The trial also allows you to use all Professional features, so you could also use that and have a play around to see if you think you would miss any of the features buy not going for Professional off the bat.