Climbing as climbing up houses, walls etc. would require maps to be updated with "interaction spots" I guess. I dont think this is possible to implement without going through every mapfile and adding those spots manually for every suitable place in all maps.
As for points needed to carry/place ladders, it would not help getting rid of the original issue. Ladders were removed so people cant build shortcuts to the flag, completely ignoring castle layouts. Even when a few people would be limited in their combat capabilities due to putting skill points into an engi-skill, the issue would still remain.