NetworkMan wrote:..............getting all this right makes a huge difference and I bet there are loads of people riding around with bikes that don't fit as well as they could. Ironically many of those are probably one with threadless steerers cut off too short so that the bars are just too low and can't easily be raised without an extension.
I'm sure you're right about that - in fact the experience of several of my cycling colleagues confirms that you are. The problem is that, once the steering tube has been cut off, having established the ideal height, there's no going back and we do change with the years. Several of my friends (of similar age to myself) are now riding their bars higher than they did when their bikes were newly built up. With quill stems you can do it. The threadless headset is, in my opinion, a retrograde step. I may be wrong about this, but I don't know of a generally available ready-built bike which has the traditional headset.
Having your frame built, and then building your own bike around it avoids a lot of problems.