The passing of quill stems? really? I have 5 bikes, 4 with threaded hadsets. One of those bikes has two "cockpits" - bar, stem, brake levers and calipers. That's 5 quill stems. An '80s Cinelli 135, a Nitto Pearl 12, a Pearl 13, a Ticycles 155 -22 and a TiCycles 175 - 27. (Plus a TiCycles 180 -17 that outlived a bike.)
Yeah, the TiCycles stems are all custom, but the Nittos are in production and easy to get. Those Pearls don't take a second seat to any stem ever made. Don't believe me? Pull one out of the box and examine the machining.
If I had better hindsight, when Geo. Bush distributed that loan from China, I would have had Ticycles make me a threaded ti stem for my good bike which was built threadless. I had them make me a -17 120 ti threadless to replace the Ritchey I set the bike up with that worked just fine but that I had zero love for. The ti is nice, but a quill would make it a better bike. Yeah, HB replacement takes a lot longer! (Every 10 years.) But simply moving the cockpit up and down for conditioning changes and specific rides is so much easier. No headset to mess with. I can do it just before I ride; it takes one wrench and maybe two minutes. Only adjustment I have to make I have to do on a threadless also. (Line the stem up with the wheel. And every quill stem I have ever owned has been much easier to sight down than any threadless.)
A poster above talked of quills being more dangerous that threadless. Yeah, I guess, if you are willing to throw out a century of knowledge. A quill stem in a steel steerer fails so seldom that most of us know no first hand (and probably no second hand) reports of them failing outside of extreme use or abuse. The room for error is far bigger than is the case with bolted, faceplated threadless stems. I almost doesn't matter how tight the quill bolt is. Yes, too tight and you can distort the steerer but very few steerers have ever fails after seeing that distortion. Too loose and it is really easy to knock the bars askew but the bike is still ridable. The single bolt bar attachment requires more attention, but if it fails, the bars almost always stay in the stem and just droop.
Big advantage of threadless - saves factory and shop time. Makes changing bars a lot faster. (But not whole cockpit changes like I do on that one bike. I don't have to mess with the headset, more than one bolt or a torque wrench. I can be hurried or careless and not pay a price for it.)
Rant, rant!
Ben