The benefits of a 50mm (or larger) objective has always been that 1) it has more surface area to gather light in low-light conditions, and 2) a larger objective will give you a larger exit pupil.

That said, #1 really isn't as big a factor these days with modern lens coatings. Personally, I've never seen an advantage of a 50mm or larger objective - in fact I view them as a negative as they force you to mount the scope further away from the centerline of the bore (which coincidentally is the exact problem them Leupold VX-L series was designed to solve). I've never found myself wanting/needing more light with a 40-44mm objective lens, even during the last minutes of legal hunting light. A 50mm or larger objective may offer an ever so slight advantage when hunting coyotes or hogs at night, but it's not going to be a hugely noticeable difference.