What they needed was another master of physical comedy. Ritter was apparently considered, too bad it didn't happen. Wass is funny, but picture him as Jack Tripper. Three's Company would never have been as much of a hit with Wass.
Much like his buddy Christopher Reeve, John Ritter was never as appreciated as he should have been...
Ritter would have been terrible. He was one of the most over-rated physical comedians on TV (on par with Chevy Chase). He didn't have the talent to carry
Peter Sellers' bags let alone his genius legacy. Not that Wass was any good.
BTW, Three's Company was an incredibly bad sitcom that comes nowhere near matching the charm of the originally Brit show it was ripping off (Man About the House). Ditto for its spin offs which were, in turn, rip offs of the Brit spin offs. Where the Brit shows relied on good writing,3's Crap-any relied on jiggling boobies and Ritter's horrible acting consisting of falling down and pulling stupid faces.
Much of the charm of the Pink Panther series lay in its European feel and setting. As soon as you make an American the star - it is ruined.