It’s kind of naive for someone to think that you’re automatically better if you switch to a stick.
If you can get your moves to come out 100% on a pad since that’s what you’re used to, then there is no reason to transition to sticks. If somebody can get their moves and strategies out 100% of the time using a guitar controller, then why should they switch? Sure it can be argued that the game was designed to be played with sticks and thus the moves should be inherently easier to perform with one. But in the end it all comes down to your ability to be consistent with your inputs and playstyle.
Even if you lose, as long as you pulled off your links, combos, punishers, etc. consistently, then people should realize that you’re a contender and not just somebody who doesn’t “know better” (to use a stick).
PS: In the Tekken community it’s not as unusual if you use pad since the games were so successful on PS1/PS2. It has much more of a pad base than SF.
PPS: Yes, MadCatz has made SF4 controllers. Just Google “Madcatz Fightpad”.