My exact thoughts when I played MK for the first time. I remember I yelled "OW! Right in the suckerbag!" the first time I saw a Finisher move. I also twitched a little whenever I saw an X Ray move. But after playing a couple of hours, I'd just say "Oh, man..." or "Huh." or just stare. It certainly lost its touch after a while. Perhaps if the new MK was strictly an arcade game, where you have to waste a couple of dollars to make it all the way to the end, then yeah. It might remain flashy for a while. But when you won the game and you're able to play it as many times as you want, then...no. Repetition is not good.
Now, it's not like I'm in love with MvC. Heck, I haven't played it in a while. But the action is fast paced! You cannot look away for a minute or else you might die. MK, though, will let you take your eyes off the screen for a second.
As a side note, this is why I don't like MOST 3D fighting games like MK. When you focus on making the characters look realistic, they cannot move as fast as, let's say, MvC, where in 5 seconds, your character can extend his arms and launch some attack, then come flying down and kick you, then summon a friend and punch you, then do a combo, then appear behind you and kill you. All in 5 seconds. With MK, it's quite easy to break an attack because you can actually see the character beginning to do that attack. Yeah, you have around a second to react but still.
For games like MK or GoW (A game that I really like), I WOULD like to see the finisher moves being saved only for boss fights. For example, allow me to kill Hades as flashy as it is. I don't need to kill its minions the same gory way over and over and over and over again. At the end, I usually just try to hit them until I see the finisher move cause I'm lazy. But if you see those finisher moves less often, they'll be more flashy later, obviously.
But alas, gore and sex sells. Those two can make up for a mediocre games.
I'm looking at you, Bayonetta.