Dear Dscribner:
I'm not an engineer, but with a reasonable number of math/physics/chemistry courses in my background before I defected towards economics, I've also got the "thinks a lot too much" issue. My wife gripes about it sometimes anyway. I don't always come to logical conclusions, but there could be worse issues to have.
Regarding your post, there really is more to the traveler than might meet the eye. For instance, positioning the traveler to windward but slacking out the mainsheet (and slacking the boom vang at bit) will allow the boom to brought to center, but will also give twist to the upper part of the sail. So in moderate/strong winds, the boat might point into the wind better without so much weather helm and heel.
There's a lot to the interplay between wind velocity, mainsheet tension, boom position, traveler position and boom vang tension. Add to that halyard tension, the cunningham, and outhaul adjustments. I certainly don't have it down pat by a long shot. But there is lots of info out there.
I use my traveler a lot depending on conditions. I remember during my basic keelboat/basic cruising course one day when a steady a 35kt wind caused almost uncontrollable weather helm even with the mainsail on the second reef, the instructor dropped the traveler to leeward. It still was struggle at the helm, but much improved.
As to why some newer boats are sans traveler, I'll let others chime in. However, I have noticed that instead of on the traveler, the main sheet anchor points on the deck for some new boats are are spread out across the beam direction. I suspect that the operator can tension one side or the other more to simulate the effect of a traveler?