I don't understand why land units are allowed to cross diagonally connected mountains(even without movement penalty). Naval units, on the other hand, cannot cross over diagonally connected land tiles as if there were canals.

See the attached screenshots.. Actually the graphics itself shows that mountains are smoothly connected even through the midpoint, i.e. not having deep valley allowing easy travel-through. Similary, the land pathway with coasts on both sides are visually 'connected'. Then why this inconsistency?

Mountain(peak) tiles in Civ4 are supposed ONLY to be natural barriers since they are impassable and yield nothing. But in reality they are hardly so. To make them real natural barriers, you need to concatenate peaks in a right angled chain, which not only looks artificial but eats up and renders useless too many tiles.

I thought this issue would have been addressed and answered already but as far as I've searched this forum I couldn't find any..