Before I let this threat RIP, I would like to share an observation.
Much of what I posted focused on counter arguments (and solutions) to tightly locking down developer workstations. To a great extent, I fell into the “solutionizing” trap. Perhaps this is what AncyC was trying to tell me 
I should have spent equal or greater effort on the case for WHY I believe change is needed, e.g. (hastily compiled – not well thought out at this point):
1) Change happens, especially in technology fields like software development. Sometimes that change is thrust upon us by customers or business partners. Developers must be able to research new tools, technologies, and techniques - even ones that may go nowhere and that would never pass a formal review/approval. Much is learned during the journey, even when/if it does not lead you to the desired destination.
2) “If the only tool you have is a hammer, it is tempting to treat everything as if it were a nail.” Often the difference between timely success and complete failure is applying just the right tool. Developers must be able to bring various, sometimes new and different, tools to bear.
3) There is no substitute for tried and true tools. In an environment requiring timely resolution of issues across widely varying technologies, it is counterproductive to strictly limit every developer to the tools preferred/selected by… who ever made the selection.
** Note: Our development team provides significant production support across many varied technologies involving clients and business partners whose technology selections we have little ability to influence.
Thanks again everyone. The discussions here helped my immeasurably.