I was Army so I know very little about the USMC and almost nothing about the Navy but I always thought that being buried at sea was done out of practical necessity.That is,you can't have a deceased Sailor or Marine on board for obvious reasons.Apart from a death at sea can a Sailor or Marine be buried at sea? It seems to me that it might even be illegal under Federal law (although I certainly could be wrong).
Also,out of curiosity (and I know it's none of my business) but if,by chance,your loved ones expressed a strong desire to be able to visit you or to have your ashes nearby would that cause you to re-think your position?
There is a whole procedure for burial at sea, reserved for honorably discharged and retired Marines and sailors.
As for family, my wife is in total agreement. Children can visit while I’m alive.