I actually don't see the difference between Ubuntu's Amazon search bar and a crapware browser toolbar.

In both cases, there are some defenses for it: it's not a terribly big problem, the developer can rationalize it in terms of obscure use cases where someone might actually want to use it, and you can always disable it once you realize it's there.

But in both cases, it's making your computer perform worse, showing you things you never asked for, and possibly breaking your expectations of privacy, just so that the developer can make a trickle of money from you.

The "crapware browser toolbar" is a browser add-on that takes extra time to load on startup, for one thing.