What I like about a regulated device is that I control the wattage to match the coil.
This is much easier than building a coil to match the wattage. This ability to control the voltage allows one
to dial in the best voltage possible. In addition as mentioned previously the regulated provides a more stable vape. You don't run into the situation that as your batteries go down your vape becomes cooler.
I also feel safer that my Mod has protections against Short Circuits and overheating. When I was using a mechanical, I once or twice ran into a situation that at the time I built the coil everything was fine, but over a period of time the coil would shift and it would short out. I also ran into a situation where a piece fell down, shorted the Mod and I had to throw it on the ground to allow the battery to discharge. A very crispy situation.
I am absolutely unable to differentiate the ramp up time or quality of the vape on a mechanical verse a regulated although there is the possibility that a connoisseur might know the difference.
In terms of maintenance I found that my mechanical had a tendency to tarnish at the connection points. I've never had to clean a regulated device but found that if I didn't regularly clean the mechanical it would lose connectivity.
Some people feel the exact opposite.
Building a coil to my preference is no different than "finding a sweet spot" with variable regulation.
The difference is that I know my sweet spot and build accordingly.
I don't have to rely on the accuracy of an aging circuit board.
As far as the vape "changing as the battery drains", its not as drastic as you imply until the battery needa to be changed.
Besides, at higher power, all but the best of boards vape differently once the batteries reach the bottom of their charge.
Lastly, all contacts will begin to lose connectivity if they arent cleaned.
Copper and brass oxidize in regulated mods just like mechs.
No magic. Just science.