I don't quite agree. Yes, critics can argue that his acting is sometimes more style than substance but I think the entertainment he provided was a much bigger factor. Also you'll see that he has explored a wide range of themes in his movies and not made the usual romance stories. A few examples
1. Hum Dono - A soldiers perspective into war and family life 2. Des Pardes - Illegal immigrants 3. Hare Rama Hare Krishna - Drugs and the hippy movement 4. Prem Pujari- A sensitive man who is forced to become a soldier 5. Jewel Thief, Mahal - proper whodunnits, mystery thrillers 6. Guide - need I say more?
Even in his later movies that weren't so successful, he had tried to explore different issues like film censorship, cricket politics and egos etc etc
And his zest for life and work is just admirable. Not that I am saying his current work is of high quality, but you simply have to give it to him for his energy for life.