Feudalism died because of Republics and the burgeoning wealth of the Merchant class. Traveller's current world model reflects the bitter transition from the Medieval Era to the Renaissance.
You shouldn't see viable large trade Imperiums because Feudal powers would try to snuff out their power and influence before they could ascent to 'large'. Notes how the Princes of Europe buried the Hansa, Venetians, and Genoese. Republics don't last long when the powers that be still exercise a belief that conquerring planets is more economically viable than just trading with those planets.
I think espoused popular values in TU are naturally in conflict with how power is distributed in the TU. It mirrors the conflicts based around peasant revolts that flooded the 15-19th century. Though about mid-17th, those revolts go from disorganized, isolated mobs to organized militias. So whichever model fits more with how planets and individuals rally such revolts against feudal states in space, would be also good to know if revolts are even a common thing in Traveller.