Tolkien never believed that a film could be made efficiently. It's not that he never wanted one made, he was more or less indifferent to it. Knowing that the technology at the time, and the production values would never measure up to what he had written. When the cartoon-'ed version were talked about and eventually made, he put his head down in shame. A cartoon?? Why not something better? In fact, Tolkien didn't even under stand the popularity of LotR and The Hobbit, and he didn't get his fans either. He didn't think they understood the magnitude of his work, and was always a little put off at the fact that everyone recognized his fantastical work, over his legitimate linguistic work and the fact he was a Beowulf scholar.
I think you're also confusing Tolkien with his son Christopher; who has widely shunned the movies and anything to do with Lord of the Rings in the media. Though apparently Christopher and J. R. R. were known to have differences and scuffles. This also has to do with the fact that Christopher and his son, no longer speak. Christopher's grandson, Royd, was IN the RotK as a Gondorian guard. Christopher Tolkien has be pretty open to the fact that everyone who likes these movies can kiss his royal ass. Everyone knows he's an old fart who, since his father died, has capitalized on his father's estate and tried to make everything his own; by digging so deep into his father's work, and publishing every last piece he can find, after he's added his own "renderings". Whether his father would have wanted it or not. And while we may have never seen some of Tolkien's greater works if it wasn't for Christopher, (The Sil being almost completely adapted by him), alot of people have criticized him for tampering with his father's stuff. Tolkien was the genius here, let us not forget.
Also, let us not forget that Tolkien gave over the rights to LotR and the Hobbit to Saul Zaentz, a film producer, (the guy that's causing so many troubles with The Hobbit, because he has an iron grip on the rights, yet he let the Rankin Bass Hobbit be made, along with the Bashki versions...*shudder*), who he knew good and well wanted to adapt the novels into films. So...yeahhh.....
I think Tolkien would have been semi-pleased with the movies. I'm sure he would have had a TON of complaints and changes, but one has to remember that books can not be fully translated to film. In order for a viewer to stay entertained and to fully follow the story line, full depth can not be achieved as it is in your imagination as your read the book. Everyone has a different imagination and a different way your mind lays out the landscape as Tolkien describes it, and the way the characters look and act.
If you ask me, I think PJ, Weta, John Howe, Alan Lee, and everyone else involved did the best that they could and gave it their all. While I don't agree with some additions and removals, I think they laid out how I view the world of Middle Earth, quite beautifully. No one else in the movie market could ever top that. The cast, the crew, the designers; everything fell into place.
*gets off high horse*