In X-Men: Days of Future Past, why doesn't professor X influence the mind of Trask instead of doing all the other effort? He does seem to influence human minds, as we saw when he changes the mind of the security guard asking him and Logan for the invitation. Why not just make Trask change his mind?
Is the answer as simple as doing this would not be so exciting to make a movie?
Potential Spoilers
It wasn't just a question of changing Trask's mind. At that point, most of the US govt was convinced of the need of sentinels due to Mystique's actions. He would have to manipulate all the people who were within that steel chamber. And at that point his psychic powers were not strong enough to do that, which is clearly seen in the film.
He would not have been able to change those many people's minds.
So, bottomline, changing Trask's mind alone wouldn't have served any purpose, as lots of other people were ready for sentinels. Trask was just the beginning. Mystique's actions towards the end showed the people that mutants were capable of being benign, and hence averting the Sentinel program altogether.
As far as telepaths were concerned, on the primary continuity of the Marvel Earth-616, Xavier's telepathic power had few equals.
With the help of Cerebro, he was capable of scanning the entire planet to discover mutants at the moment of their power's genesis.
Even without Cerebro, he was capable of scanning and telepathic communication with thousands of minds, persuasion of hundreds of minds, coercion of dozens of minds, domination and control of several minds simultaneously and even the complete erasure of a single mind, even one as powerful as Magneto's.
Did the Days of Future Past continuity version of Charles Xavier have the same powers and abilities? Yes. But there were extenuating circumstances.
In Days of Future Past, he had been suppressing his powers by use of a genetic cocktail which temporarily negated his powers while allowing him to walk. During this movie, we never see younger Xavier exercising the full range of his telepathic/psychic abilities.
By the time, Trask has been discovered, mutants had already been outed and governments roused by the fear of Homo Superior presented by Trask. He might have only had a chance to prevent Trask from doing what he had done, if his powers had been active while Trask was attempting to raise money and interest in his Sentinel program.
Older Xavier knew this, which is why he did not volunteer to go into the past. He already knew at the point they were discussing, he had no powers and would be of limited help.
Young Xavier's powers were far too weak to affect all the minds necessary AT THE TIME, to make them forget what they had seen. With the cameras beaming Magneto's betrayal and Mystique's change of heart, Xavier would have had to be able to blank the minds of everyone on the planet who had seen this broadcast.
Could he, in the future, decide to try and retroactively correct or adjust people's perception of mutants in small groups?
