I've got no objections if someone wants to convert the Olympic class liners for IL2, but I will point out that:
Titanic - sank in 1911 - before WWI.
Brittanic - was a hospital ship in the Mediterranean during WWI. It didn't participate in any significant military actions and sank in 1916 after hitting a mine laid by a submarine.
Olympic - was a troop ship during WWI and didn't participate in any significant military actions (although she did sink a German submarine by ramming). She was scrapped in 1935 - well before WW2.
So, while the Titanic and her sister ships are some of the most famous ships in history, they're insignificant from a military point of view.
Given the very long list of ships that aren't yet in IL2, which saw significant military action, I think it's misdirected effort to try to convert these ships for IL2, and stupid media-driven fanboy-ism to ask for them.
It makes about as much sense to ask for the Nina, the Pinta and the Santa Maria, a Viking longship, or the HMS Beagle or Bounty. Famous ships indeed, but more appropriate to an entirely different game.