Motorola, Samsung, LG, HTC, Huawei, and more apply their own custom user-interfaces atop of the Android operating system. However, the question that should be asked is what is so wrong with the operating system that makes that custom UI useful? Launchers and other interfaces that can be put on top of stock Android can potentially slow down and make for an unstable experience. This is one reason that many users avoid Android is because it looks so different across the manufacturers that Google allows to use it. With the advent of Android 4.0 (Ice Cream Sandwich) Google has told manufacturers that they must keep the original coding their to ensure that apps work properly so end-users (you, the customer) do not suffer in the end.
As a Samsung Galaxy Nexus owner, I have become more and more of an Android purist and these themes and customizations appear more useless and cluttering everyday. The user should decide what their phone looks like and has on it, including the pre-installed bloatware that manufacturers love to put on devices in order to get you to spend money.
Bottom line: Pay close attention to Android devices that are released and you will deem this as an issue to. Simple is best, Android is about customization; but it is best left up to the user.