Not just variety, but utility also...
Why does anybody bother with thumb safeties then? If the only concern is not being able to just pull the trigger accidentally, why don't all guns just use grip safeties (aside from variety)?
The original part name used by the US ARMY for the thumb safety on a 1911 was "safety lock". This name was still in the shop manuals when I used them in the 1970s. Its a good name, and describes the intended function fairly well. "Thumb safety" only describes the location.
We "bother" with safeties (such as a safety lock) because, unlike a grip safety, they require a separate, conscious action to engage and disengage them.
A pistol with a grip safety is mechanically safe, but one with a manual safety is operationally safer.
According to what I have heard, it was the Cavalry that insisted on having the safety lock (thumb safety) on the 1911. Browning's prototypes only had a grip safety. The concern was a cavalryman trying to reholster a loaded cocked pistol with only a grip safety could result in an accidental discharge. Being able to "lock" the gun on safe was considered desirable, back then.
And, it is still desirable for a lot of us today. This is the point of a manual safety, it only goes on when you want it to, and it only comes OFF when you want it to.
There are many, many circumstances when I still want the gun on safe, while I am holding it in a firing grip. A grip safety is good, but I am more comfortable with a grip safety AND a manual safety. I am also comfortable with a manual safety alone. I am also ok with no mechanical safety at all. One just has to use the proper manual of arms for the gun in question in order to be safe.
If you aren't ok with a manual safety, simply don't use it, and rely on the safety between your ears alone. (note that while it does work, that safety often fails as well).