If you think about this from a management point of view, the reason they may be doing this is for legal compliance. The company is responsible to ensure that every tool used is being used legally and will also not encumber the product that is being developed. (Some editors are free for personal use, but not free for any other purposes, etc.) To audit every tool that every developer may want to use can be expensive. I've seen that on projects where time lines are tight, management will be cautious about which tools/libraries/etc are used to minimize changes later in the project that are directed by the legal folks.

On higher security projects there is also the concern of where the IDEs store temporary files, and what information is stored between sessions.