Understanding vector physics can help you win in smash bros? Absolutely! That's what it's all about. In a typical fighting game there is a Rock Paper Scissors system between attacks, dodges and throws, but with smash bros there are so many other layers on top of that basic system. Magic/energy, absorb, reflect. Charge, counter, barrage with projectiles. Cumulate damage, distract, go for a launch (smash).
Simply recognizing that there are light-weight characters and heavy-weight characters can really improve your game. You have a better chance of finishing a light-weight with a vertical smash, and a better chance of finishing a heavy-weight with a horizontal smash. Certain characters have significant horizontal AND vertical recovery moves, so you're better off using quick, weak cumulitive damage attacks to get their % high enough for a successful launch.
There is also my tendency to get so invested in a fight that I have to fight the urge to launch my 3DS across the room in frustration...
Considering the level of complexity and the appeal of the characters I'm surprised that smash bros STILL isn't taken more seriously as a fighting game. I guess because the controls are so simple that it feels like a step backwards to the guys who have had to memorize long-ass button combos to do well in typical fighting games. Also, it's just not even marketed to those guys. If there were a smash bros machine at my local arcade I would never leave!
I have a feeling with this latest installment, there will be more immitators like the Shonen Jump and Naruto fighting games on the game cube years ago, but nothing compares with smash bros. Smash bros for 3DS has got me hooked. I hate to sound like such a fan boy, but after the outrage about tripping in Brawl, and Brawl's terrible online system, it looks like Nintendo decided to listen to their fans. Similar to how FF14 became a proper MMORPG instead of the experimental crap it was to begin with, smash bros has become a fine tuned work of art with incredible potential for complex mind games and quick thinking exploits.