I recently bought a cheap android device because I needed to test something on Android. The setup was about 3 hours of the device starting up, asking me questions, installing apps I explicitly told it not to, and then all sorts of other apps and OS updates trying to do their thing seemingly at once. I wasn't even transferring data, just a brand new phone, new google account. What a horrible experience you get with so…
Consumers often have a choice, at least between "filled to the brim with crap" and "a modicum of crap", by choosing between buying their phone from a store or from a carrier. Carriers have better deals but shovel their phones full of the worst apps you can imagine. Still, people will buy the crap-filled experience that makes you want to tear your hair out because they like the idea of scoring a better deal.
Nothing like unadulterated greed combined with short-sighed consumer behaviour at scale to drive a market segment into an awful race to the bottom.