Narrower beam producing a better ship seems counterintuitive to me

When I narrow the beam for the Ger/BB/1907 down to 90ft, I seem to produce a better ship. The speed is somewhat higher and the metacentric height is reasonable: 3.27ft at normal load and 4.68ft at deep load. The displacement comes down to 24,948 tons for the normal displacement. The design goal was 25,000 tons, so this works very nicely. The thing is, why shouldn't a 105ft beam work? Isn't more, better, even for beam?