It's been brought up before here. Their territory's breadth makes it harder to hold, since their armies have to spend so much time in transit to get from one end to the other. From my experience, two-front wars practically seal their doom, and these have always happened in the opening months of my campaigns. Strugia shouldn't be smaller, it should be reshaped to be less of a ribbon. Shrinking Strugia would be a band-aid fix, allowing them to use their western choke point more effectively, but it obviously shrinks their economic and manpower base.
I would like to see the whole overworld map reworked, but it's secondary to getting core gameplay mechanics right now. The map doesn't have to be fully balanced, but it should give every AI kingdom a decent chance to win early wars.