The Spine Trial has all features (except saving). If Spine Essential also had all features, it would be the same as Spine Professional.
Spine Essential is a low cost version that has limited features. It is far from "useless". The difference between developing a game without using Spine Essential and doing so using it is huge. It lacks advanced features in Spine Professional but it provides the basics and that can be useful for many things.
We suggest learning the basics first anyway. Many get bogged down with advanced features before learning the basics. Misapplying the advanced features makes a huge mess of your projects. You can upgrade to Professional for the difference in price any time in the future, so money spent on Essential is not lose, and certainly not "stolen".
This is all done with Spine Essential:
http://esotericsoftware.com/files/Gamasutra-Carlos-Cavalcante-Tips-to-create-funny-and-juicy-character-animations-with-Spine-basics/
Spine Essential also provides a lower cost way to use the Spine Runtimes. Licensing Spine grants rights to use the Spine Runtimes. Sometimes people will obtain Spine exports from others and want to use the Spine Runtimes. They can purchase Spine Essential to do so, even if their Spine exports use Professional features.
We believe in the value Spine provides, including our top notch support. You are getting answer from the owner of the company 2 hours after you post. Also consider that we do not charge for updates. You get ALL future updates for free, for life, without needing to pay again. We do a LOT of updates:
http://esotericsoftware.com/spine-changelog/archive
If you don't believe Spine provides enough value to warrant its price, feel free to consider alternatives (none of which are very good). Also consider how much of your time it would take to develop something similar (a lot of time), and how much your time is worth.
Please note that this forum is a friendly place. You won't be rude here again.