Funny how SP described this as a technical issue related to older hardware not being able to handle more monsters onscreen. Their long promised "solution" to those people, and is to essentially bilk them for more gems/money.
Since monsters in the vault dont generate gold, you're actually paying for less efficiency. If you dont need the gold, and just want to tidy up your islands, you're paying for a place to store your junk monsters that you'll likely never even use.
I'm pretty sure that after Take-Two bought SP, they simply view these mobile games as cash cows rather than actual games. They likely do not care if the game goes bust because of this crap, they likely just want to milk it for all they can get before it dies. The direction the game has taken certainly seems to imply this.
Basically, all your complaints will fall on deaf ears, and the game will continue to be built around making more money instead of creating an enjoyable experience. Every new feature will just be a new way to punish players that dont spent a ton of money on the game.
For those that've spent a lot of time on the game, and dont want to totally toss it, but want to see if SP actually 'is' still open to positive changes if theyre pushed.. I'd suggest not buying anymore gems of course, but also do not watch ads, or complete "tasks" in monsterwood for gems. SP earns a profit from this as well.