You're probably right that many "tactical" flashlights are a little overbuilt on purpose, but generally that is not a bad thing per se.

Aluminum tubing is not that strong to begin with, even with a quality alloy. A wall thickness of 1mm is pretty darn thin and will not stand up to any serious abuse. Double that thickness and you might come up with something exponentially more robust. Leave another milimeter or so to ensure proper tolerance/battery clearance and you are basically at somewhere around 0.59".

I used to EDC a Maglite Solitaire on a key chain back in the days before powerful LED lights and I was never really that impressed. Different strokes for different folks but on paper at least the new Surefire seems a pretty good all-around design, by no means too overbuilt for reasonable EDC.

Then again, I personally prefer a decent 1xAA light (I carry a Nitecore at the moment). It is a little bulkier but hardly so much as to be impractical as far as general EDC.

P.S.: Technically speaking I find it hard to believe that any remotely reputable production plant (in China or elsewhere) would have difficulty coming up with properly centered aluminum tubing.

I would expect that the flashlight body is assembled from semiproducts already finished to pretty tight specs, which is not difficult to obtain nowadays. Machine the side a little bit to remove some material for sleek design and weight reduction, add the head and cap assembly, anodize and that's pretty much it. Hardly rocket science and and a heckuva less complicated than something like an iPad ... or even an AK rifle, which the Chinese can churn out by the thousand.