I certainly see the ability to stretch a boat for little more money....you just have to see the big picture....
A good example of that is what happened to the new Clipper range here in Oz, following on from the classic Chung Hwa boats like mine.
Initially, they did make a new version of the Clipper (as they are called here on Oz) 34. Then came the 38, which was larger in all dimensions, as Eric mentioned. However, it had a short, chopped off looking cockpit, (they are all sedan or Europa style now), so the stretched the hull to 40', and it looked just right. But 34 owners then wanted more room, eg a second for'd stateroom, so the retired the 34' moulds, and chopped down the ex-38' mould to 36, so now we have the Clipper 36', which is longer, wider and deeper than the old 34, although looks about the same size, but of course quite a bit more expensive.
Now the 40' which I think is still a lovely boat, and was the flagship for about 10 years, is being overtaken by the newer, larger Cordova 45 and 48 series, and now there is a 52, and even a 55 I think.
Fortunately, there are still quite a few of the 34s, 36s, and 40s around, and the 36 & 40s can still be ordered new, but you are looking upwards of $300, & $500 respectively, so out of my league...