that's not true, brawl is actually soothing and energetic at the same time
I don't need a game to soothe me, what is this, video game therapy? Melee is fun for me, so I play it, Brawl is not very fun for me, so I don't play it (much).
To refer to the first post, and generally just the title of this thread: what is your reason for 'becoming pro'? If you feel the desire to improve and show your skill in Melee, because you enjoy the game, that's reason enough to competitively and improve. If you're playing the game just to make money or gain fame in the community, I don't think you're playing for the right reasons.
Also, if by 'pro' you mean 'really really good', then I say yes, it's worth it, provided you can find some people to play against. I find Melee gets more and more fun as I get better at it, because so many more options open up, and there's a ridiculously high potential for improvement. In the end though, if you don't have the drive to improve and get to that level, then there's no other reason. It's not like you can simply put a bit of time in here and there and reach your full potential, you have to strongly desire improvement, and seek it actively. If you're too lazy to do this, Brawl might be for you. >_>