ARR doesn't want us to abuse other musicians like Raja. As fans, we should respect that. I would never say bad things about a legend like Raja, anyway. He is an important part of the holy trinity of Tamil Film Music (along with MSV and ARR). But, Bala is not a musician. I'm not sure if he is musically qualified to comment about Rahman's music. Granted he decides the technicians for his movies and he has the right to choose anyone. He could have simply said "Raja has done a great job for me in "Sethu", "Pithamagan" and "Naan Kadavul" and Yuvan has done a good job in "Nandha". So, I never thought of going to someone else for the musical needs of my films". Rather he says, with surety, that Rahman's music would not have worked for his films. That borders on arrogance. But, I wouldn't blame him; the hopeless tamil media talks about him as if he is the next incarnation of Akira Kurosawa and this man probably believes that. IMHO, his movies are not that great - granted they are different but that doesn't necessarily translate to great. He is good but not extraordinary. One thing is true - Raja has given extraordinary music for his movies.
Anyway, who cares what Bala thinks? He is not the be all and end all of cinema. Rahman has conquered great heights and he will continue his great work and please his millions of fans. He has faced criticism from a lot of people the last 17 years and has answered them all in style. Listen to what Balamurali Krishna says about Rahman now. The same BMK, the legend he is, didn't have so much good to say about Rahman few years back. Same with Raja. Now he is hailing him as a phenomenal musician. I'm not blaming these wonderful musicians for not talking great about Rahman in the past. But, he has earned their praise. That is more important. In addition, there are a host of great/good directors working with Rahman and countless others queuing up to work with him.