I guess I have seen only a few of his movies but they are enough to convince that he was a wonderful director. A few of things that I have often noticed in his movies and only in his movies.
1) He took the high-brow stuff to the middle-brow audience. In “Unnal mudiyum Thambi”, Gemini accuses Kamal of using “Asutha Dhanyasi” for singing to the labourers. But KB did that repeatedly too. He introduced Carnatic Music and made it look less intimidating to the rest of us. Surely the songs that are shown in the sabhas (in Aboorva Raagangal, Sindhu Bairavi or Unnal mudiyum Thambi”) were made easier for an average cine-goer to enjoy, but he also did it without pissing off the real Carnatic people. Rajini’s question to Thengai Srinivasan and the “Enna Samayalo” number also bring out a fun version of this much intimidating art form.
2) The same could be said of the apt use of Bharathiyaar Kavithaigal in his many movies. There is something intimidating about reading poetry, but the use in KB’s movies does a marked service to the audience.
3) KB’s older movies were more about lower middle class and in the 80s and 90s he started to depict the upper middle class too. I think this started around the time he himself had more money than he used to. He neither treated the richer people with contempt in his older movies, nor treated the poorer people as non-entities in his later movies. Like Actress Bama of Bama Vijayam being friendly around the common people next door and the old man who plants plenty of trees in U-M-Thambi. The relationship the domestic help has around their masters is always shown and their personality is always touched upon lightly. For some reason, this is a rare thing in the works of other directors.
4) As an extension of point 3, Sowcar Janaki’s character Meenakshi Doraiswami(MD) is depicted as a socialite. As she herself later says “Enga Party nnu alaiva”. Her quirks like taking a photographer to capture her moments with celebrites are touched upon affectionately but never looked down upon. She is such a loveable personality and surely the only lovable socialite I ever saw in Tamil Cinema. Also, there is a scene where she goes and visits Uma to gift her a saree. Apart from showing that their relationship has gone beyond acting before Thengai Srinivasan and is truly affectionate, it also makes the movie pass the Bechdel Test. Both of them are named characters who talk to each other about something other than a man.
5) He also had the habit of never showing certain characters on screen at all. From Irumal Thatha to Malgova Maami’s husband. Such impact these characters have on the story.
6) When he made a mistake, he was willing to acknowledge it. He had the lovers commit sucide in “Ek Duuje Ke Liye’ but started the story of a failed suicide attempt in Punnagai Mannan and argued against suicide as best as he could. Later he made Vaanamea Ellai to analyse the topic more deeply. It was a preachy movie. Still.
I am planning to watch a few more of his movies and know about him better. For what is the use in complaining about popular tamil directors do not do justice to their subject matter, if you do not sit watch the ones who did a terrific job during their time?