Depends on said complexity.
You listed three notes above. (A) is odd. For (B), similar packages should be obtainable unless it's a proprietary package for your startup. (C) Encryption is pretty well supported on OS X and Linux. Scratch Windows.
I'm sure some devs would welcome a new laptop. However, being restricted to just that without good reason will strike most as odd. Trust your devs to be able to setup their own dev environment. Allow other environments if they can make it work.
At the end of the day, it seems like the underlying message is what counts. Does it appear that you are encouraging or dictating ?