Gripe about terrain: frozen rivers vs. swamps

[Kamerer]

I understand the limits of designing the game, but something that seems to continually irk and baffle me after a lot of play is the radical difference between frozen rivers vs. swamps.

Frozen rivers seem to be treated as open terrain; no close combat. But frozen swamps still force close combat. To the simple analysis, it should be the other way around. Swamps are level terrain (it's what makes them swamps), rivers not necessarily so. In a frozen scenario, the swamp should be the quicker one to yield to open/maneuver combat. A generic swamp will always feeze quicker and more level than a generic embanked river.

Just baffles me in every winter scenario.