The MA GOP (or at least most of the statewide candidates, anyway) succeeded in divorcing itself from the national party. Like the old Southern Democrats, they just go along with the local majority on basically all social issues. The fact that the Dem vote is so evenly distributed throughout the state also helps with this. There is essentially no base for a national Republican larger than a state house district.
The CA GOP is very rural/exurban and dominated by conservative activists. The median CA GOP primary voter basically agrees with the national party, so there is little motivation to moderate, and there's a base of safe R seats in the legislature and US House.
NY is more complicated and it does have some history of MA GOP style candidates, but at least in recent times, NYC and all the media attention it draws keeps things nationalized. This has been especially true post-2010.
Vermont is a more extreme version of Massachusetts on these points.
This is a big one. CA and NY are so large that they still have vast areas of republican voters.
