This comment is pretty far off the mark.
You are absolutely correct that the differences between the lines are getting smaller and smaller. Especially with customization, you can basically an EFLex that is an Axis 2 with Knee rolls. Brian's will do the same. Vaughn's stiff pads are not very stiff. Most brands are going with 1 style boot break, 1 strapping set up, and then a choice of stiffness profile and knees rolls or not.
Where you should do a bit more homework is on Bauer. Bauer probably has the biggest difference between lines right now. Just because 1 lines does not have knee rolls does not mean a thing.
Bauer has 2 completely different boot break angles, strapping set ups, knee block flex profiles, calf plate flex profiles, and there is a major difference in comparing their stiffness. This does not get into the difference with the blockers and gloves.
Why is everyone generally going to 1 basic pad setup? People basically want the same things these days.