Attacking Capitals -- What does it do?

[Belenus]

I suggest you try to hold one or two of their cities. That gives you a good base of power in Italy, plus though 4,000 men won't go to waste and can still be used. A suicide raiding force sounds good, but with all those men, you might as well go to Italy and stay.

[D. Boon's Ghost]

With Rome, herself, taken, the other Roman factions carry on as they always will; they won't erupt into revolt, they won't bother to reclaim Rome, etc.
The AI Romans don't actually have any ties to the Roman Senate, I believe.

This, to me, is really odd. It doesn't make sense that the Senate is nothing more than eye candy when playing as a Non-Roman. I mean... they don't had out missions to the AI Romans, they don't attempt to acquire land, they don't do much of anything but sail their hundreds of ships back and forth.
I think it would be nicer if the Romans played as one huge faction when playing against them. I have yet to see Julii, for example, helping out the Brutii while I, the Macedons, crush them into the pavement. You would think that the second you landed troops on the Italian boot, every single Roman (no matter the color) would rush to kick you off.

[Bob the Insane]

I mean... they don't had out missions to the AI Romans.

While I agree with most of what you say, I am not sure about this point as when playing non-Roman factions the Roman factions appear to regularly attack the same locations as the Senate often order me to (when I do play a Roman faction) at least in the early part of the game...

As for the Senate faction not expanding I think that has more to do with their orginal placing on the map. I sold them a Gaul province once I did not want (playing as the Scipii) and next thing you know they are doing better against the Gauls than the Julii!!!

The Barbarian Europa lot are putting together a mod where they are considering having only the Senate faction... The only issue I see with that would be that the game would play as if there is a sole ruler of Roman (Emperor?) for the begining due to the way the factions work...

[Patricius]

I only ever saw the Senate expanding through bribery. I have never seen them expand by conquering cities. If capital cities fall there should be, if there is not already, a loss of most of the treasury of the faction losing the capital.

[Sin Qua Non]

As for the Senate faction not expanding I think that has more to do with their orginal placing on the map. I sold them a Gaul province once I did not want (playing as the Scipii) and next thing you know they are doing better against the Gauls than the Julii!!!

I have got to try this! That should make an interesting late game scenario.