I have a M&P.
Although, I have heard the primitive-specific S&W 180D also lacks the peephole feature, but instead utilizes a hole at the end of the barrel and trigger for such purposes. I think it's called the E-Z View. You primitives should check that feature out.
It is just one of the many ridiculous requirements Massachusetts has that applies to all handguns sold there. Others included in the list below.
Performance Test , Limits of Accuracy Test , Metallurgical Test, Drop Test,
10 lb Trigger Pull, Hidden Serial Number ,Loaded Round Indicator or Magazine Disconnect, Detailed Safety Briefing and Disclosures ,approved Lock (from Dealer) .
This is just a few of the reasons many manufactures do not sell in Mass, I have been told that the cost for these tests is approx $50,000 not including the multiple guns in each configuration (eg. Stainless,rail,no rail etc.) that are needed to perform the testing on with a few of the tests being destructive.