Regarding Allen Ludden, in Betty White's book "Here We Go Again", Betty said that Allen could at times be blatantly honest, and sometimes being TOO honest could get them into trouble. That likely came into play with Password and Password Plus. Ludden was obviously not a fan of the lenient judging early in the run of Password Plus ("Firewoman" was accepted for the clue "Fireman") but it's likely they did that to get celebs and contestants comfortable with the game, then the judging got more strict when they became more accustomed to the game and the puzzle format. Also, because opposites were being used too often for clues, they decided to have a "no opposite" rule. Ludden seemed to have reservations about this change too, but it did make the game more interesting to watch.
Also, with Password All Stars, there were so many format changes and too many layers. This included adding a DOUBLE option in the main game, the option being decided by flashing arrows, and the complicated scoring of the bonus game. Scoring each celeb individually for the final show also must've been a headache. Just watch Ludden host the finale. On the surface it's business as usual, but one can also tell that Ludden didn't like waiting for the flashing arrows, and you can tell he's thinking "geez this is a lot to explain" when he's breaking down the scoring during the bonus game.
It's interesting with Richard Dawson's excellent playing skills that he never appeared on Password Plus, but it's also no surprise considering Felscher produced that show too. Then again, Felscher also produced Password All Stars, but if Dawson had any ego problems, they weren't evident in 1975 because this was before Family Feud. In fact, watch any episode of Match Game '75, Dawson was at his peak and seemed quite happy in general.