It’s true that the Jefferson Memorial and the Lincoln Memorial are not visible to one another. I think there is a reason for that, whether or not it was a conscious factor in the Mall’s design. Abraham Lincoln didn’t see eye to eye with Jefferson. In fact, his vision of government was quite different. While the Declaration of Independence clearly provides that individuals can alter or abolish their government, Lincoln adamantly proclaimed that the Union, and by extension the federal government, was to be perpetual. In fact, after he repeatedly ignored and even violated provisions of the Constitution, suspended habeas corpus, imprisoned journalists, publishers, newspaper owners, citizens and seized their property, waged war without a declaration, etc, he sought a resolution from Congress to excuse those violations.
http://ncrenegade.com/editorial/history-speaks-through-the-monuments-on-the-national-mall/