Getting a good grip on a handgun is important.
Once the gun is solidly within hand, the shooting
technique may be dictated by the circumstances. Some techniques favored by some folks may be disadvantageous under different conditions.
Then again, maybe some particular shooter will be lucky and only have to use their handgun under conditions favorable to using their
preferred technique.
In gaming/competitive venues this is pretty much something that's known in advance. In real life, non-sporting applications, things can be less predictable.
I'm not rigidly attached to any specific shooting
technique with handguns, any more than I am with one specific striking technique (martial arts) using one of my hands.
Someone who wants to consider themselves properly skilled and well versed with shooting a handgun under all manner of possible circumstances might be best served to be able to shoot 1-handed, using either hand, and 2-handed, also using either hand (as the "master" hand for a 2-handed grip).
Sometimes the size & weight of a particular handgun may lend itself to being fired more easily with one hand. Sometimes not.
Making precise shots with a handgun at 50, 75 & 100 yd distances is often easier for many folks to do when using 2-hands, especially when shooting heavier, hard recoiling Magnum revolvers. Large handguns can get heavy as the rounds rack up. Spreading the weight between 2 hands/arms can be helpful in holding & steadying handguns. (Especially on days when you're feeling brisk gusts of wind trying to move the gun's sights off that itty bitty target down range.
)
Why does this have to be a "one or the other" thing, anyway?
I like to keep my skillset well-rounded. Why not? Might be handy at some point.