The change can be justified on neutral principles. Committees more closely resemble the legislature as a whole, which makes legislating more feasible -- and party leaders and members accountable to the voters.
The downside, in some critics' view, is that the election of chairmen also gave would-be chairmen motives to raise money for other members, very often from K Street lobbyists.
Many Class of 1974 members proved to be productive legislators. Waxman, who ousted a more senior chairman of a health subcommittee in 1978, sponsored bipartisan laws on generic drugs and orphan drugs (for rare diseases), forced expansion of Medicaid in the Reagan years, shaped the 1990 Clean Air Act and pushed Obamacare and cap-and-trade through the House in 2009-10.
Miller worked with John Boehner and Edward Kennedy on the Education Act of 2001. Harkin helped lead the bipartisan move to double funding for the National Institutes of Health over five years. Baucus led Senate Finance Democrats for 13 years.
The Class of 1974 also shifted the House and the congressional Democratic Party from hawkish to dovish. One of its first acts in March 1975 was to block funding for South Vietnam when it was under attack by the North. Saigon fell in April.
In the 1980s, the Democratic House kept pushing back on the Reagan foreign policy. In 2002, Nancy Pelosi, who holds the seat once held by Phil Burton, led most House Democrats to oppose the Iraq war resolution.
Pelosi says she is staying on, even as her ally Waxman and her consigliere, Miller, leave the House. The 201-member caucus she leads has more black and Hispanic members and fewer young doves and reformers than the 291-member caucus Waxman and Miller entered nearly 40 years ago.
Still, the Class of 1974 has left a mark on history -- though not as much as one Democrat who narrowly lost a House race that year, a 28-year-old Arkansan named Bill Clinton.