What is the point of military access?

[PhoenixFury23]

And why are even close allies unwilling to give it up?

It's not like the original total war where I need your permission to travel through your land otherwise it means a declaration of war... I just walk strait through. No damage done, except perhaps to your relations, but it seems minor in the grand scheme so long as you're only making passes through and not loitering around.

[Lord Feloric's Ambassador]

The other factions will be upset if you pass through their land, your army unknowingly ravages the countryside. It's seen as an act of war. However, trying to gain military access is barely worth it; you will most likely end up turning on your allies sooner or later anyway.

[A Freaky Name]

Military access prevents your army from running into a neutral/allied army and getting stuck there until the end of turn and of course prevents loss of relations. Getting stuck is an issue easily avoided by using spies to scout ahead of the army and relations aren't an issue if you're already at war with them (and you're winning), what other good reason could there be for wandering around another kingdom's territory?

Its easy enough to get from allies if you have a solid enough reputation, but as the good ambassador mentioned, hardly worth it.

[Conquistatore]

Military access allows you to traverse your allies land free of danger and molestation. You are mostly safe from enemies, suffer no decrease in relations and can easily transport your troops across allied lands to aid in a battle or reinforce a distant region.

[Hetairoi]

As I play mostly orthodox factions, military access with catholic allies is a must, if you don't want half of europe to got to declare war against you.