I think rahman should be assessed in toto and not on basis of last few years or few albums also quite a lot of his work is still unkown to Bollywood. The problem is that we get used to a good thing very quickly and in such a way that we start expecting more and more from that. He's getting predictable-"has been a reaction that started with his first few films only. The people who dismissed Rahman were mostly seen to be from the earlier generation. But again these people could not tolerate the music of Anu Malik either. The magic of yesteryear songs are still prevalent among this generation at least up to us. Only two days ago Pyarelal of L-P duo have said Rahman is not outstanding, not long ago Ravindra jain said mai unka (Rahman ka)sangeet samajh nahi paata.
Hmm lets analyse this. The doyens of yesteryears songs would mainly focus on melody, sur and semiclassical format not giving a lot of importance to instruments arrangement and orchestration, in fact R D Burman also got some beating for same. AFAI understand Rahman's music is shockingly western, this I realised for the first time when I listened to Thiruda-Thiruda songs, it is ironical that I went to see this film in a theatre which had no subtitles in Hindi or English, because right from onset of Roja I knew some one has arrived in the music. But yet there is an Indian soul lurking behind. For example in malargale while the harmonic progression is western (of violin choir) and arpeggio providing rhythm with bass drone, singers are singing lyrics over raag Hamir kalyan.
I think a lot of feeling about being repititive is because ARR has strong singnature styles, his orchestration is unique and can't be imitated, this is why they sound same though one would certainly find some thing different inside.