Though at one time I did see the  possible need of accommodating more clan members there, I was never convinced of the necessity to actually physically enlarge it (by so much) on the map. 

It just created confusion,which has only worsened as the level of the stronghold has been increased, and more so since the way the game is currently played,with strongholds springing up all over the place,( don't say you didn't notice and don't know why that is.)

Many of the clans at least in my kingdom, and  I am not about to do a survey of all of them,appear to have no  way near 125 clan members, so they do not need to be so big now?

I do not think much casting out of towns in close proximity takes place,(perhaps it does) but most all these new strongholds are both overlapping and enclosing the best yielding tiles,even in the forest,and maybe yielding inside is still frowned on,and so is a risky venture, especially where there is much overlap,and disputed ownership and different rules administered.

So do they really need to be so big now?

Can they not be shrunk?