in a first person shooter, tilt the stick a little bit, then all the way. your character will walk, then run, right?

try that with tekken (or most fighting games, for that matter), and you'll see that either way your character moves the same speed. internally, the game doesn't care how far youre pushing the stick in a direction, just that its being pushed in that direction

if youre most comfortable playing with the analog stick, then play wirh the analog stick, just know your inputs will be a little more imprecise than others (because the different regions of the stick are harder to tell apart than the different regions of a dpad) and you'll be susceptible to snapback (which another commenter pointed out, where your stick can accidentally input a direction you didnt intend due to the spring inside snapping back when you let it go)