"Optical design advantages", "inferior 50mm obj", "dreaded 30mm tube".
Curious what you meant by that.
Just as with most other optical devices meant to be viewed with the human eye, a large ocular lens group can provide a larger eye box, wider field of view and in some cases easier long term viewing. As we approach the theoretical limits in optics design, optical engineers are using every "trick in the book" to gain even a small (often times inconsequential) advantage over the competition. Larger glass at either end is one way to do it, especially as the "zoom" range and magnification increases. The references to 50mm objectives and 30mm tubes were just a satirical jab at those that don't like them for a variety of reasons and consider them a "minus" in rifle scope design. It's just the "intelligent posterior" in me speaking out.