Sudden change of market conditions.
Hewlett-Packard used Canon laser engines, but they were first to market and promoted the LaserJet, LaserJet II and LaserJet III skillfully, dominating the market.
Canon also aggressively sold laser printers in the U.S., and destroyed the reputation of non-HP lasers. By contract, Canon was forbidden to sell an HP compatible printer. All other manufacturers were HP compatible, but enough people bought Canons and had severe driver problems, few would buy non-HP printers. Even Panasonic had a hell of a time getting any market share for their dual tray 5051, which was a very fine machine at an excellent price.
Then, Canon came out with the faster 600-dot engine later used in the LaserJet IV, and they went to Hewlett-Packard and told them. "We're going to be using this engine, and we're going to sell this engine to anyone else who wants it, but, unless you let us off this compatibility issue, we won't sell it to you."
Hewlett-Packard dropped the compatibility issue, and got the 600-dot engine, but they realized that without Canon out their spoiling the compatible market, they were now going to have to be price competitive. They designed accordingly.
Could they have sold a heftier printer at a higher price? Yes, but not if they wanted to be the volume leader, and that's what they wanted to be.
