That's not a minor advantage, that's an HUGE advantage and actually, an huge safety feature along with not really having to worry about doing two functions at the same time. Pretty much removes most of it out of the equation.
A self leveling loader prevents the operator from spilling the material with a bucket or a log with the forks on their lap when they're lifting the loader high. There have been loads of cases of this happening with people getting seriously injured or even killed and this is a big reason why self leveling loaders are becoming more and more standard on a lot of countries all over the world.
The self leveling loaders that use an hydraulic self leveling valve often lose position which makes for a weird experience and often only work when lifting. The ones that use either a parallel mechanical linkage or two feed back cylinders offer a lot better experience for the operator, plus it works both ways, lifting or lowering the loader.