It's a shameful money grab that we were one of the last clubs to adopt. Everton started the trend in this country about 20 years ago.
Last time we had a home kit that lasted more than 2 years was in 1975 (not counting the 1997-2000 European home shirt - a money grabbing outlier).
It's just really odd to me, but of course my perspective comes from the USA. If you look at MLB, the NFL, NBA, etc, most teams create a set of home and away uniforms and stick with them for literally decades. Most now have 3rd uniforms as well, which sometimes change every few years, but sometimes stay for decades as well.
Ever since Nike became the official uniform supplier of the NBA a few seasons ago, things have gotten out of control. Some teams literally have 5 different jerseys each season. It's ridiculous, but of course they're printing money as fans love to buy all these different jerseys and ultimately that's the decisive factor in all this.
If I had my way, United would go back to Nike, have them design a simple, classy home kit for us that we stick with for several seasons. Then make an away kit that stays for at least 2 seasons at a time, and let them go crazy on third kits that change every season.