Last year, for the anniversary, the two base strongholds went for 3 credits (e.g. the number of years TOR has been active).
Last year, for a totally new player, 3 credits v. 5000 credits was much easier to achieve, so therefore it was more of a boon.
This year, not so much given the money that showers down upon you from quests. But the 4 credit cost is keeping with the tradition of lowering the cost of strongholds.