Even as if it doesn't mean anything in the grand scheme of things, it's a flagship named after your capital, having it sunk is not good on morale.
I'd like to see how Russia will spin this.

Imagine being so petty that rather than admiting you lost a ship to enemy fire you claim that you lost a ship that can withstand a nuclear blast to heavy wind and rain on a big lake. Yeaaah i'm sure this won't make you look even more retarded and incompetent russia… Everything according to plan.