Believe it or not (hey, this is Microsoft), this build is all about security. More accurately it's about improvements and new features in Windows Defender, Windows Defender Application Guard, and probably most importantly, Windows Exploit Protection.
To quote Microsoft:
"We’ve heard your feedback regarding the upcoming EMET EOL, so we’re excited to announce that starting with this build you can now audit, configure, and manage Windows system and application exploit mitigation settings right from the Windows Defender Security Center! You don’t need to be using Windows Defender Antivirus to take advantage of these settings.
After upgrading to this build, you can find these settings by opening the Windows Defender Security Center and going to the App & browser control page:
- Either right-click the icon in the notification area on the taskbar and click Open, or search via the Start menu for Windows Defender Security Center
- From Windows Defender Security Center, click on App & browser control and then scroll to the bottom of the resulting screen to find Exploit Protection
More detailed documentation will follow on Microsoft Docs, and remember that Exploit Protection is a work-in-progress and might not be fully functional just yet!"
Microsoft's full release notes are here: https://blogs.windows.com/windowsexperience/2017/06/28/announcing-windows-10-insider-preview-build-16232-pc-build-15228-mobile/#8QMkrcxPf2Ji8r0r.97