It was wrong of them to betray Lord Nerevar, but they did do great things for the people of Morrowind for thousands of years. Vivec, in particular, saved the Dunmer countless times, hence why they named the city Vivec after him. After losing god-status, Vivec used what little power he had left to restructure the Tribunal Temple and assist the Dunmer while he still had the chance.  So, it's not a black or white answer to say if the Tribunal were bad people for betraying the Chimer's greatest hero. In the end, all had the best interests of Morrowind at heart; they just had different visions on how to achieve their goals.