Lucas should definitely stop messing with Star Wars
The Lord of the Rings movies are pretty good. They do differ quite a lot from the books though. The key people involved may have been Tolkien fans but I think they put what they thought was for the good of the movie's success above keeping true to the books. In no way are they "as accurate as possible".
Most of it is typical hollywood stuff. Bigger action scenes, cutting out "slow" parts or character development that didn't seem necessary to the story, inflating the love interest. Almost everything Arwen does in the movie is made up. Either it never existed at all, or her actions originally were performed by a different character. If you didn't read the books first you won't notice it, but if you're familiar then you're going to jump up and say "Hey, what just happened there!"
If you're interested, take a look at this page for a list of many of the differences:
Watching the extended edition versions helps some, as some of the cut scenes are restored and I recommend doing so if you can.
Now, on to Lovecraft... ANY movie can be remade, and if you can at least roughly as good a job as the older version and there's enough of an audience who wants to see it then it seems to me that it would be a good decision to do so. It's BAD remakes that really stick in the craw, someone clearly had no respect for the source material and just tried to mangle it for financial gain most likely.
The problem we face here is the audience bit. We have hard PROOF that people will pay money to see even bad Star Wars movies. I'm sure a new Lord of the Rings would be successful once enough time has passed and if it could be well done. In fact, they're working on The Hobbit right now which is planned to be a 2-movie deal. I've already warned my wife that when both of them are out on DVD we'll be doing an all-day event to watch all five extended edition movies in sequence! She has several years to prepare for this.
I don't know that we have enough audience for Lovecraft though. Those who love the mythos LOVE it, but the public at large is still not that aware of it which is a huge problem for movies. It's going to take some raising of awareness before I think we see much being spent to make mythos films.