It's the government's own term, used by nonpartisan entities like the CBO.

If anything, "welfare" is now used as a more politically loaded term. It's almost never used anymore without attaching a negative connotation -- whether by the right in the old way, or by the left when decrying "corporate welfare".

Politicians can't refer to social programs as "welfare" because it carries a negative connotation, and people on Medicare, Medicaid, and Social Security will be uncomfortable with being grouped with those on SNAP. They also can't refer to them as "social programs" because it's three short letters away from "socialism."

The use of the word "entitlements" is a lot like how socially left-leaning people are now more commonly referred to as "progressives" rather than "liberals."