Lincoln was ridiculed unmercifully by his opponents, of which there were very many. Some powerful leaders within the Republican party often referred to him as "the ape". Criticism is part and parcel of the Presidency.
Just as cruel kids will goad a fellow when they find his weakness, the press and political opponents will hunt the President's weak spot. Trump used this technique to great effect during the Republican primaries.
The Trump Administration better find a way to pick and choose which media battles to fight or they will find themselves in paranoid everyone-is-out-to-get-us Nixonian mode. Picking a fight over the size of inauguration crowds is not only silly, but a waste of time. Who cares? Any casual TV viewer could see the empty bleachers on the parade route. Anyone with even the most rudimentary interest in politics is aware that the new President is a divisive figure and that even Congressmen were skipping the inauguration. The fight over crowd size is dumb, counterproductive, and spends credibility capital for no reason.
We know press secretaries are paid flacks (read liars for their boss when necessary), but to start right out of the gate with a Baghdad Bob whopper is no way to get respect. If we cannot trust you on the little inconsequential things why would we believe you when it matters?