Your coach is behaving like a life manager, not a coach.
A coach should teach you how to show, how to evaluate what classes you should be entering and how to set yourself up for year end success, not be filling out your forms for you and telling you where to sign.
However, you are not behaving like a student either.
A student needs to listen to their coach and the reasons for not entering a certain class. A student needs to listen and learn how to evaluate what classes to enter.
I fill out all my own entries, but enter classes based on what my coach has suggested. I was ecstatic when I was allowed to enter the I1 this year, and allowed to do an I1 Freestyle and allowed to ride the whole shebang in a CDI. And now because I have waited to enter those classes, I am totally confirmed and go out and have a great time. It is such an awesome feeling to me to be schooling at home things that are above the level I'm showing and to be able to waltz into the show ring and do the test without worrying about things being confirmed or not. And I thank my coach for pushing me to wait and train over winter so that I can now succeed at the higher level.
The difference in jumping between 1.00 and 1.20 is HUGE and not just by 20 cm, the courses are far more technical, the distances are tougher and it requires a certain finesse and technicality to ride at that higher level that can take a winter to develop.
If you are bored at the level, then yes, stop showing so you can begin your training for winter now. Start schooling more technical courses at a lower height, start improving your riding through flat work and become a thinking rider. I think George Morris is an awesome experience and I hope that the way he pushes you (or shoves you, or throws you down on the ground and beats you) will really show you what it is like to be a rider at the higher and higher levels. It becomes so much less about the height of the fences and so much more about set up, striding, riding and details, details, details. Riding higher levels is not about how high the fences are, it's about who has the best foundation of basic riding and training.
They say money doesn't buy happiness -- well happiness doesn't buy horses!