How do you get this far into a thread of "game show changes for the worse" without mentioning JackPot! switching from riddles to straight questions at the end of its NBC run?
(IMO, getting rid of the target number at the same time was almost as bad.)
While I'm at it:
1980s Dream House changing from three-choice questions to two.
Celebrity Sweepstakes getting rid of contestants having to write down answers - while it did get rid of the possibility of two celebrities giving the same wrong answer, it also prevented questions from being scratched.
1970s Sale of the Century switching to a two-couples format.
Getting rid of the "moneyball", and then getting rid of the prize for hitting all seven bumpers, on The Magnificent Marble Machine - it made the whole point of playing the machine anti-climactic.
Password modifying its all-star format to use regular players; they should have just gone back to the original format.
Speaking of adding celebrities to a show, sometimes it works (I think Monty Hall Beat the Clock was better with celebs), and sometimes it's a headscratcher (All-Star Baffle, where what the celebrities did really meant nothing as each pair was playing for a studio audience member who then played the end game).