Is there polling on this or is this just anecdotal?

This polling suggests that 59% of the state overall wants to see improvements to public transportation as a top transportation priority for the governor: https://www.massincpolling.com/the-topline/massachusetts-poll-78-of-voters-view-transportation-system-in-only-fair-or-poor-condition-59-support-future-mbta-shutdowns-to-expedite-improvements

73% of the state also supports transforming the commuter rail into a true regional rail network. While I am sure there are people outside the Boston metro (which is more like outside 495, not 128), and even within it, who want to gut the MBTA, I'm not sure there is evidence that there is a "vast majority", particularly if we are talking outside 128 as opposed to outside 495.

It is true that 62% of those polled supported making towns and cities within 128 contribute more to the T, but it's worth noting that 64% of voters within 128 itself supported this, so shifting the funding burden of the T more towards Boston and surrounding communities was actually slightly more popular within 128 than it was statewide. Which is a bit surprising.

Most of those towns and cities have existing Transit Authorities.

Merging them under a single umbrella, statewide so that they had a uniform budget, uniform standards, a uniform fleet of vehicles (and just like toilet paper, if you buy busses in bulk, each one is cheaper than if you buy them one at a time). Apportion the state money available based on both population, and level of service. Let those various towns then pour some of their own money in to the LOCAL system if they choose.

Service literally everywhere would improve.