Trying to compare the cabin of a 38 powerquest, and a 38 lightning, is not a fair comparison. Its like in the 80's, when wellcraft made the 42FT excalibur eagle. Huge cabins, amenities, 6ft headroom, etc. Does that mean in 1986 the 42 wellcraft was better than a 41 apache? The guy buying the apache has different ideas for his boating. Same goes for today.
I will say the cabin in my 38 is small compared to say a Top Gun cabin. Its not due to the length, but rather the hull design. The fountains hullsides do not flare out like a top gun, which makes it narrower in the cabin. Plus it is a lower freeboard boat. So you do lose some height and width.