I have never been a fan of MDR lobster and there have been many "lobster nights" that I have ordered something else.
I love lobster but the tiny, frozen, warm water lobster tails aren't that good. Having said that I did notice that on my last Carnival Liberty cruise, while the overall food quality had diminished, the size of the lobster tails had increased. I had a bite of my daughter's and it wasn't bad.
Choosing your own lobster from a tank might be a nice idea for one of the alternative restaurants but I don't think I would want to stand in line to "choose" my lobster.