This SharePoint Designer lockdown debate has long been centered on the potential chaos that can occur should it be allowed, but I say those days are over! Empowering workers does not mean simply opening the floodgate to a mess of hodge-podge development. Those who build solutions love the platform and do not want to jeopardize what they have created. Smart Power Users recognize the opportunity to master Designer as a career opportunity, and the last thing they want to do is jeopardize that with rogue development. The exchange of configuration documentation as a concession for empowerment is an advantageous arrangement for both sides.
The platform is at risk when anyone developing solutions is missing fundamental SharePoint understanding. Those who jump directly into Visual Studio without first mastering out-of-the-box options can cause far more damage than any Power User with access to Designer. The outcome of such ignorance is often revealed years after a fool’s departure, when all upgrade attempts are thwarted because some “reinvent the wheel,” business-critical solution was created in Visual Studio instead of using two content types and an out-of-the-box workflow (all without a note of documentation).