When you have your stem slammed and you are riding the drops, your center of gravity is lower. It makes it easier to rail turns which is why almost ALL of the professional cyclists have their stem slammed.
Do you think going around a turn at a high speed with a high center of gravity is safer? Think about it...
When your in the drops, the lower you can get yourself the more streamlined you are and the faster you can go. But, you need to look up which places stress on your neck. It's hard to descend for a long period of time for me being and 'older' guy...
Yes, that's what i meant. For a race with closed roads it is perfect. Because speed is all that matters. But riding on public roads, one would want to be sitting a bit more upright to be able to see oncoming traffic earlier.
And then as you mention, comfort. Craning your neck at an awkward angle is not possible for longer durations. Even if we remove the age factor.
You know one of the good things about your bike is that you can set it up any way you want. My setup is for racing, even through I do not race, it is setup for maximum speed. I specifically sacrifice comfort for speed.
If I were ever to get another road bike, it would probably either be a touring bike or a gravel bike. I would not slam the stem so I could ride it for hours without discomfort.