Saying Mortal Kombat sucks is like saying all fighters suck. Those games were and still are the pinnacle of innovation for the genre. We got finishers, combos, weapons kombat, and the elusive "gaint unhuman sub boss" all from the mk series. Also we got the boss that clones other characters from mk.
Not to start an argument, but... Ah, heck, why not? You are wrong on a few points. First off, innovation and execution are two completely different things. Just because a game includes something in some form doesn't make it good. Yes, Mortal Kombat was the among the first games to include finishers, but they did exist in other games of the time. (see Time Killers, released the same year as MK1). Weapons combat? (introduced in MK4) - Again, see Time Killers. Combos? (Assuming you're talking about the counted combos and dial-a-combos included in MK3) See Killer Instinct (for Dial-a-Combo), or the Street Fighter Series (for Counted Combo), both of which were released at least a year before MK3. Now, I'm not saying any of these games are better than Mortal Kombat, but a lot of the "innovations" you mention had been done before. Mortal Kombat 1 was a revolutionary game, but the sequels left a lot to be desired.
My thoughts on Pinnacles of Innovation for the genre? Why, I'm so glad you asked.
Street Fighter II - Brought the Modern Fighting game concept to life. Yes, other fighting games existed, but the characters, story, and special moves of SFII were something fresh and new.
Mortal Kombat - The original was a remarkably innovative title. The use of video captured characters to create a sense of realism. Projectile attacks that did more than just damage a player (Freeze, scorpion's spear, etc). Then there's the Finishers, whose existence almost single handedly brought about the ESRB. (Yes, I know what I said above about the finishers, but I was refuting them being a "first" for MK, not their historical importance)
Virtua Fighter - 3d Combat, even if awkward and confusing.
Tekken 2 - The first time 3d combat was done close to right, creating a good flow to the fight.
Soul Calibur - Movement Freedom, and the most depth-balanced fighting game I've ever played. (Def. "Depth Balance" - New players aren't overwhelmed by the control scheme, and can execute good looking moves, but experienced players still can use the fighting system to full advantage)
Power Stone - Interactivity with elements in the fighting arena.