For instance the REO has an exposed negative spring where you can place the negative side of the battery on the spring so it's nice and grounded, push down on the battery and have plenty of room for clearance to slide the positive side of the battery under the positive contact of the mod. One of the great features of the REO. It's ingenious as the spring also tells you if your mod is overloaded. If there is a short the spring will collapse rendering the mod useless and safe until you install another spring after fixing the short or rebuilding your coil to a resistance that the mod can handle.
YOu described that REO action perfectly. Clearances are generous.
I had a short when I first started vaping on one, spring dropped down immediately,,,, it took me a few seconds to realize what happened, because I pressed button and got nothing, then realized the battery was loose / floppy inside the REO ..... then light went on in my brain. It wasn't even a bit scary, contact was broken immediately when spring dropped and no tension on battery anymore.
Of interest, as a newbie, I started out with better stuff (provari / REO) and then later bought bunces of chinese stuff out of curiosity and thus began my "education" with wrestling batteries into badly engineered tubes/sled modules, receiving batts that were manufactured in a different height every few months (Vmod), mods that ripped and chipped the wrappers on my batts, mods in 2012 with improper or no real venting, having to use ribbons and tape to get batts in or out gracefully, etc. (First time I held an istick and those buttons "rattle". Yeah, it's only $35 but I'd rather spend 100 more not to have something rattle in my hand every time I pick it up.

)
It's all in the engineering. Better batteries have better wrappers, better C ratings, better mods have better clearances, as do better chargers, etc.
One thing I know: IF I were looking to get a mechanical mod now, knowing all that
can go wrong, I"d get the "better" batts, "better" charger, and "better" mod .....or i would wait til I could afford those.
The way I look at it, even the most knowledgeable vaper can have a day when they are tired, when they are not paying attention, when they haven't inspected their mod and/or battery that "one" time, when they are rushing, etc.. We all get side-tracked, we all get lazy.
We have all reached over to grab something in the passenger seat while driving, too, I'm sure.....perfect way to drift a little into a ditch...
The idea of "ever vigilent" while vaping......not sure I WANT that in my life, since I smoked to relax, and vape to relax as well.
That said, there is a reason to have at least one trusty mechanical in one's arsenal and I'm certainly not AGAINST mechs in any way shape or form.
I'd say any mod where you have to wrestle the battery in or out of the mod is a bad investment though. I could not deal with doing that several times a day, 7 days a week......