No more detail is required. You didn't get what you wanted. You got what the Navy needed. Don't take it up the chain, because it's not going to change anything other than making you look like a whiny bitch.
I had two classmates that were former Marines, and wanted to go Marine Corps after graduation. They both got SWO. They both got drunk, then focused on being the best SWO they could be. They are both now LCDRs, one is a CEC officer, the other a MH-60S pilot (after having flown MH-53Es). They both love their life, and wouldn't want to change anything.
Either accept your service assignment, and realize that you've been given an incredible opportunity - a free education, a JOB (not so easy to find these days); or quit - and either repay the Academy, or go enlisted. But don't bitch about it.