Importance of combos in fighting games?

I used to play mortal kombat as a little kid (failed horribly at it) but it was still fun i saw the new mortal kombat was coming out and wondered if my troubles with learning combos should stop me buying it? I recently bought marvel vs capcom 2 i seriously dont know how im supposed to Learn the chars THERES LIKE 50 OF THEM AND THEY ALL HAVE LIKE 6 COMBOS so anyway ive forgotten if Mortal Kombat is as big on combos as marvel vs capcom 2? If so i may not buy it i would really like to play fighting games but learning the moves is bullshit for me