What's actually happening is more subtle than the doomsayers would have you believe.
Doomsayer? I'm a doomsayer for demanding my money's worth, well in that case the Apocolypse is coming, duck, cover and stick your head between your knees.
It so happens that when a saved game is loaded, the AI does a reassessment of its position, decides what is relevant, and then acts
Between the time I save and the time I load know how many things change? 0, unless of course the computer gnomes are accessing my save files and launching a Sythian invasion of Italy.
It's also a consequence of getting the AI to look after its interests during play. After all, many players review their overall position when reloading a game, send armies to new destinations, decide that a siege isn't worth pursuing, or simply reassign attack priorities in the light of their strategic reassessment. The decision was made that this was a reasonable and sensible thing for the AI to do as well: the loading of a game seemed like a good point to get the AI to sit back and go "hmmm... what's happening?... maybe those guys should be doing something more useful..."
maybe those guys should be doing something more useful like sitting in that patch of trees for a few turns. Gotta let the city defenders rest, fair play and all that.

There is one of two problems here:
1) There is a bug
2) The AI is built on a faulty premise which is *tada a bug.

So I say to you CA, you have kicked your core out. We are the ones who buy the games. You think joeblow who bought RTW is gonna buy The Next One: Total War, hell no, he's got his fun.

Anyway email game mags, sites, anyone. As money seems to be the drive