Entrenchment is better as the additions are right there in your face, but you don't have to use them if your strategy doesn't call for them.  It adds new content to the game without changing the core game.  The additions are all in the form of early-mid game defensive options, and makes the AI more interesting as it will make good use of these options, so mastery of the game certainly isn't required to benefit from them.

Diplomacy is more subtle, and the changes do affect the game at the core level.  While it's a general improvement to the game, it makes things more complicated for inexperienced players.  If you play the game a lot, it's a no-brainer.  If you only play it occasionally, it's safe to pass on.

Play an aggressive AI and then a fortifier AI or economist AI.  It's like day and night.  The aggressive AI plays the game like original Sins; it masses lots of ships and attacks.  This is not difficult or exciting to beat, and I don't mean having to exploit it with a chokepoint starbase or Marza.  I also didn't load up Sins to play C&C.  The fortifier AI and economist AIs build a much more balanced empire, building up their defences and economy while slowly building up a fleet.  This is much more difficult to beat and more importantly fun to play against.  A late game fortifier AI is not easy to take out, and you will pay dearly for every planet you take from them.

But yes, I will agree the Visari AI is at a loss when dealing with chokepoint starbases.  But nobody has a gun to your head forcing you to exploit the AI to win.