In reply to The Answer Guy.

The average WordPress user expects the plugin to be installed and activated.

Requiring them to click to install a plugin and then click to activate the plugin adds an unnecessary step to the process in order to cater to developers and power users who don't want the plugin activated immediately simply doesn't make sense from a user experience standpoint.

WordPress should be streamlining things and making things easier for the average user. That's more than just making existing behavior look pretty without actually changing the existing behavior. You need to actually make it easier. Not just look nicer.

The vast majority of users are clicking to install the plugin and then immediately clicking again to activate the plugin. Why not make that process more streamlined?

Just like core background automatic updates the behavior should be streamlined for the average user and then a hook can be used to modify that behavior for developers and power users.

The whole point of this change is to make WordPress a better experience for the average user. Hiding this functionality behind a hook defeats the purpose because the very type of user this functionality is geared towards is the type of user that you don't really want fiddling with hooks.