For users of devices other than a Nexus or Moto X - which also offers a nearly bloat-free OS - this means they can take advantage of the core pieces of Android and the larger Google ecosystem. In other words, you can customize a Samsung or HTC device how you see fit. It's like Google is making what we commonly refer to as "stock" Android another skin, but in separate apps so that users can choose exactly what they want. Since last April, users have been able to install a standalone Camera app built by Google, while Gmail, Maps, Messenger and Calendar have their own individual software, too.
In addition, there's a standalone Google Now launcher available for download. That piece of software puts the handy card-based virtual assistant a swipe away and brings "OK Google" voice controls to the device of your choosing. Other handset and tablet manufacturers are set on draping Android in a custom cloak, but Google is making sure users have a choice. Don't like the way the clock looks on your Samsung Galaxy S6? Want easy access to Google Now on that HTC One M9? The idea of these separate add-ons, especially the Google Now launcher, gives you a way to ditch Sense or TouchWiz for Google's own vision. Mountain View is giving you the means to swap in its Nexus-style tools by releasing key pieces of the operating system through its app store. This also means that the company can update the core experience without having to wait for the next version of Android to push big changes.
Google isn't limiting itself to Android's features, either. It's also breaking its core services up into individual apps. For example, Drive had the tools for editing Docs, Sheets and Slides before Google turned them into separate apps. This gives users direct access to what's needed to create a spreadsheet or tweak a presentation without having to dive through Drive's menus. More importantly, it also means that if you only plan to use Sheets, you don't have to download Slides as well. And most recently Google separated Photos from its home within Google+. Obviously, it still ties into Google's web services, but it's another step in building a Google Experience that's no longer anchored to "stock" Android.
See, Google realizes that the ability to skin and customize Android is part of what makes it so appealing to phone manufacturers. But, it's also what makes it so appealing to users. And the company wants to make sure that if you want a "pure" Google experience, you can get it, even if you buy your phone from Samsung.