I think the fact that you view it as necessarily the "smart" decision shows just how deep the misunderstanding goes about the reasoning for this rule in the first place.
Why, in real-world terms, would it be "smart" to put your capital city—the seat of your entire realm's government—on the front line of a war? Remember, the fact that it is also your sole recruitment base is an OOC restriction intended to maintain gameplay balance.
Frankly, it's comments like these that make me want to implement stiff penalties for having your capital sacked, or even just losing a battle there to any significant number of enemy troops. Maybe if, say, tax collection was suspended for two full weeks after such an event due to the civil turmoil, people might think twice about the front line being a strategically "smart" place for their capital....
And frankly if that were implemented, I'd have no trouble with it. You have to judge the risks in warfare. Just as military commanders make judgements on how close supply depots should be to the front line while still being relatively safe from attack; the closer your capital is to the front line, the more risk you take in the city being sacked and made unusable for recruiting. I still don't see how it could be considered a strategic capital move in the rules sense if they lost their previous one.
Besides that, why should we be forced to roleplay our characters as logically thinking? If I want my character (assuming he becomes Ruler some day) to move the capital after the previous one went rogue/seceded/changed realms to one that is close to where the enemy is because he wants to spite the enemy, why can't I?
