Venki,
That's because you're looking at it if it was black or white. Neither. It's a fine shade of grey which is a special Raaja genre by itself called "mensogam" (melliya sogam), one that encompasses longing, trepidation, betrayal, dejection and myriad other feelings of the "disappointment to unhappy to sad to devastation" band. "Pathos" at its artistic best. Not explicit in announcing its emotions with a big bang, rather it's a feeling that creeps on you just as the mist envelops the mountaintop on what was a clear sunny day minutes ago. If you didn't understand it from Suka's or Raja_Fan's perspective, you're perhaps cast from a different emotional stone. How does Raaja evoke this? Alchemy, known to the exalted few. Without having to resort to vocal histrionics or obviously emotive instrumentation (which he does when he has go the whole distance or be blatant), it's also so well integrated into the format of a 'nature song' or 'female solo' or a 'romantic duet' that the lay listener can enjoy it for its sheer melodic content even if he/she didn't quite get to the emotional core. Perhaps, it requires something akin to an "Intel Inside" campaign to alert listeners to this very subtle, subliminal range of emotions embedded in the conventional film song format. There are literally hundreds, but let me just leave with 5 examples that are top of mind:

1 Uravugal Thodarkathai (Aval Appadithan)
2 Alli Thantha Bhoomi (Nandu)
3 Azhagiya Kanne (Uthiripookkal)
4 Ye Thendrale (Nenjathai Killathe)
5 Athikalai Nerame (Meendum Oru Kaathal Kathai)