Aye comrade, that would be grand. but for now those Worgen refugees need someplace to stay. rebuilding Theramore shows the Alliance leader that the Worgen can contribute to the Alliance and they are not just some helpless refugees by taking the responsibility of maintaining one of the most important Alliance footholds in Kalimdor.
perhaps after the reconstruction of Theramore the Alliance will be more willing to help the Worgens in retaking Gilneas.
Gilneas is already accessible but theres nothing in there. no NPCs, no quests, nothing. Maybe the issue is that Blizzard doesn't want to make a city so close to the Undercity, implementing that can have serious consequences especially in Silverpine where lowbie Horde players quest.