I understand Blizzard wants ICC to last until Cataclysm with it being the end of this expansion. I also like that they gave a Role Playing reason to the gated progression and limited attempts.
How I see things:
The Argent Crusade and Ebon Blade have joined forces to form the Ashen Verdict. An army to battle Arthas and his scourge minions in ICC.
And like any army, if you are unable to take the hill, you fall back and regroup. You call in reinforcements and go and try to take the hill again.
Once you have taken the first hill you are able to set up a larger base camp and gather more reinforcements which allows you a larger army to cross the river and take the second hill.