My opinion would be that using a skill like FF6's Blitz attacks with Sabin could be pretty cool, though I would steer clear of making it THE way to use skills in the game. That style of command, while fun for some (I always used Sabin

), is not for many. It worked well in FF6 because you weren't forced into using it for the game. Some people just suck at quickly typing specific sequences of buttons, and many of these people are fans of RPG's for this reason, since that talent is not usually a requirement for one, but usually reserved for action/fighting type games.
As Boba Fett Link said, the appeal of your game would be limited if it was always required, so just keep that in mind. I would love to see "Blitz" style skills incorporated for certain characters, classes, or skills, though.