Wow, if they were alphabetical before, I never noticed that. Sure there were letters at the top of each panel, but those were simply for location purposes and repeated in every row. I'm sure they needed some sort of plan for spreading them out from the start, so it does make sense that there could be a specific order.
As others have mentioned, however, keeping them in alphabetical order throughout 7-8 years of sales would be impossible, particularly because Disney had no way of predicting how much space they would need for a particular letter. Each monolith differed in size as you got closer to SSE, so I'm not sure how they could keep it alphabetical. I'm not saying you're definitely wrong, I just can't wrap my brain around how that could work.
With the new setup they certainly could have alphabetized them. This would be mostly useless to those of us with tiles though since there are no names on them. You'd only know that your last name that starts with "S" would fall on one of maybe a dozen or more wall sections. Really cool that they finally created a website with this info, it certainly beats bugging a CM in a store or at guest relations.