Harts vs. Honky/Valentine wasn't exactly a "filler match". The two teams had a feud going on, which started in December 1988 on "Superstars". It was just a continuation of Jimmy Hart fighting the Hart Foundation.
It was an interesting feud, though, as it was mostly played out in singles matches. Hammer would pair off with Anvil, while Honky paired off with Hitman. They ran house shows from December through March and WM5 was the blow-off. So it was another experiment in the "Bret Hart Singles Push/Tease".
Also, the original broadcast had a stupid intermission. Mean Gene came on (backstage) to make a "major announcement"-- Hulk Hogan would be starring in "No Holds Barred". Then they ran the movie trailer.
They also had an interview with Sensational Sherri, who claimed to be the hottest thing in the WWF (with her pot belly). She also took a few shots at Liz, foreshadowing her involvement with Macho Man.
The whole Liz/Hogan angle is STILL very creepy to this day. I like how you point out that Macho should have been the face in the angle.