Roy,
Because that geometry is fast as blazes and works well, that's why. The problem you fear does not in practice present much of a problem. I use such SKs daily above 20 WPM - actually, for everything under my 25 WPM bug.
All my fastest keys, my Frattini (Marconi) and NATO, my Begali, as well as the Scandinavian keys use a similar geometry.
Dave is very knowledgeable about them.
I bought one of those "Silver Cicada's" when they first came out last year, although they didn't have that fancy name, and the boxes weren't ready - but I didn't care. Those are made from solid stainless which is twice the weight of the others which are made from aluminum. The steel is the deal.
My gaps are usually tiny - down around .001. But I don't measure them - I measure at the knob and go for .004. But I don't usually measure that either - I just set it by feel - very tight, very crisp on both the up and down. But recently I was asked about gaps and took measurements.
The contacts on the key I got are in fact junk, one is - something - and the other, well it looks like something broke off. But once clamped down, it is fast, nonetheless. In the $130 range, I think that key is a bargain. But I would want the stainless steel, not the lighter aluminum.
I like the design enough that I've toyed with the idea of having one made with the same frame design but doing the details right, finicky gold contacts, micrometer adjustment for gap and tension... oh drool... That would be sweet.
My NATO key that looks like it dropped from the butt of a Czechoslovakian tank during the cold war has a micrometer for adjusting it down to a gap in the .001" range. That's my second fastest key.
Anyway, nice keys.
73 Chris NW6V