OMG, they're coming after us (H.R. 347)

[ProSense]

40. Did

"But why is it being changed now after all these decades?"

...you miss this:

BACKGROUND AND NEED FOR THE LEGISLATION
The United States Secret Service provides protective services to the President, the First Family, the Vice President, former Presidents, visiting heads of state, and others. This protection covers not only the White House and its grounds but also any where a protectee may be temporarily visiting. The Secret Service also provides protection at events designated as `a special event of national significance.'

Current law prohibits unlawful entries upon any restricted building or ground where the President, Vice President or other protectee is temporarily visiting. However, there is no Federal law that expressly prohibits unlawful entry to the White House and its grounds or the Vice President's residence and its grounds.

The Secret Service must therefore rely upon a provision in the District of Columbia Code, which addresses only minor misdemeanor infractions, when someone attempts to or successfully trespasses upon the grounds of the White House or Vice President's residence or, worse, breaches the White House or Vice President's residence itself.

H.R. 347 remedies this problem by specifically including the White House, the Vice President's residence, and their respective grounds in the definition of restricted buildings and grounds for purposes of Section 1752.

The bill also clarifies that the penalties in Section 1752 of title 18 apply to those who knowingly enter or remain in any restricted building or grounds without lawful authority to do so. Current law does not include this important element. The bill makes other technical improvements to the existing law. In the 111th Congress, the House approved similar legislation (H.R. 2780) by voice vote on July 27, 2010.

There is nothing sinister there. The update first passed the House in 2010. It was re-introduced in 2011.