So you're doing exactly as was intended by the feature to begin with?
You're basically asking for the removal of an inconvenience.
The point of class changing was the fact you're supposed to pick one and stick with it, not because of the rewards but because changing your class like you would weapons defeats the entire point of the system in place.
I know some high level players have little patience for anything that slows their flow, but it's honestly a little ridiculous to request things that are completely counter-intuitive to the cash intake of the game. Similarly to those asking for the new armor to be sold for diamonds, it's just not gonna happen.
If Gems of War has any chance of being a long running game, it needs money, and the 5 dollar switch versus 6 day wait seems quite reasonable for a single feature. Especially considering higher leveled players would use it the most often, and are also the ones making the most diamonds in a day.
Now if you wanted the price reduced to, say, 25 gems, I'd understand your plight.
Or if you asked for the wait to be reduced to, say, 3 days.
But complete removal is a no-no. If you can't wait, you spend. If you can't spend, you wait.