My opinion on this, after ruminating over it, is that a few things are possible.
1) A plurality of MA residents may be less aware of their respective RTAs than they are of the MBTA. Thus, RTAs provide valuable services that potential riders are unaware of.
2) the RTAs are bad at cross jurisdictional transit, whether it be to the T or each other.
3) The current organizational setup where the RTAs are independent agencies with independent governing boards is detrimental to an integrated transit system.
The MassDOT Rail & Transit Division (RTD) is effectively powerless and functionally only serves to direct state grant funding to the RTAs, other transit orgs and to collate data from them. Plus, the 15 RTAs are required by state law to outsource basically all of their operations. Checking my notes... WRTA itself has exactly *8* full time employees. LRTA has 6. They do not need independent contracting, payroll, procurement staffs.
I'd propose a new org chart, reforming RTD - The 15 RTAs should be merged, such that they are a single corporate entity, with the CEO embodied in the role of the RTD administrator, who in turn should be a dual report to the MBTA GM & MassDOT Sec. In essence, in my view the RTAs can continue to act as independently funded, regionally branded operating divisions of a single transit entity answering to a single governing authority, as appointed by the state - then give that authority a mandate to interoperate with the T/ intrastate regional bus. Given that the state provides a substantial majority of their operating funding, the current advisory boards can continue in that role - they already don't exercise any day-to day oversight.
RTD's statewide rail functions can go to MBTA, and its RTA competitive grant process could be made functionally redundant. Ideally, such an integrated system would be able to prioritize resources internally, and incentivise multimodal statewide connectivity instead of independent RTA fiefdoms.