That is not accurate. Science thrives on controversy, even einstein theory of relativity. There are areas of scientific development that challenge the core ideas in relativity, like the speed of light is variable and time is not relative. Based on my understanding, TOE is firmly established as mainstream science, more so than the big bang theory. It has a lot more evidence and supported by cross science disciplines. That said, no scientists I read will stop questioning TOE or any scientific theory and regarded them as the final TOE (theory of everything).

So why particularly TOE is singled out as a highly doubtful science theory and many people are reluctant to accept it's findings? The reason may well lie in religious belief. There are some who find that the ideas we come from "chance" and "monkey" are simply disgusting.
No, in science an established theory means much more than the layman quip " It's just a theory". Yes, a theory can still be proven to be false or inaccurate. But there is a big difference between the false and inaccurate. Let's take an analogy. If you start with a theory, say by looking at the sky the sun appears to run around the earth, so stating that sun rotates around the earth. This of course is proven to be false. So the theory is abandoned and replaced by a new theory supported by some observations that earth rotates in a circular orbit around the sun. When more observations pour in, more data is acquired, more accurately we understand the law of gravitation, we found that it is not exactly in a circular orbit. It's in an elliptical orbit. You may then ask how true is this elliptical orbit if we were to take into account slight perturbation due to relativistic effects and so on.

Hence, TOE is correct to conclude human and monkeys shared some ancient ancestor some millions years but controversies that are raging within the scientific community are mainly the details like how each humanoid fossil is linked, what causes speciation, what were the environment etc ...