allie,

All presidents lie.  Just like you and I do, and just like all attorneys, doctors, cops, school teachers, bartenders, and husbands and wives.  Would you truly want a president, or any of the others, tell you the stone-cold truth each and every time and in any and all circumstances?  There have been many, many science fiction tales that have explored just such situations (mind reading being just one variation) and each and every one evolved into a nightmare. 

Take Trump publicly stating that FEMA assistance to hurricane ravaged Puerto Rico is not forever.  That's just the unvarnished truth, and admittedly a warning as well.  Still, was he praised for his forthrightness?  Of course not, because it was not helpful to say it under the circumstances.  But it was, indeed, the truth was it not?