You need to know before hand what the hidden features are though. Trouble is that you can't easily find it out. If you check customer reviews you will almost always find glowing positive reviews for things just dripping with DRM. Though to be fair, when I see a glowing review I almost always think that there must be something suspicious, because no one can get that excited about a mere consumer product. Plus these reviews usually get written long before the problems are discovered, which means you have to wait a year maybe before some more honest and objective reviews show up.
People LOVE the Blu-Ray despite the horrendous DRM it has. People still buy Origin games. People somehow are quivering with delight at Keurig despite the alternatives that don't have DRM.
The problem here is not the high margin on replacement parts, but on the DRM itself. I can make an adapter for a Gillette razor if I wanted to without breaking any DMCA laws. Inkjet cartridges did not originally have DRM but instead just some ominous "for best results please only official parts" warnings. And of course people figure out the do-it-yourself solutions pretty quickly, until the manufacturers figure out how to change software to prevent the DIY.
As well, with the razors, the blade is the real product and the handle is merely a free accessory. The ink cartridges require a really specialized formula (easy to replicate from a third party of course). But for a cat box cartridge it's just a plastic container full of soap and water, there's nothing special going on there except the dimensions and interfaces of the container.
For the profits, this may work out well at first. But after awhile people will stop buying them. Negative word of mouth gets around. Maybe they make less money overall than if they just raised the base price at the start. After all, there are a lot of people out there who are perfectly willing to buy the "official" replacement cartridges.