Its not difficult at all, but I find it unnecessary. A tribe of 25 is small enough that any micro comparisons of looking at 10 or 15 were, in my opinion, unimportant. If I were to get feedback from a bunch of players that this is something they find important, I would look at my decision and consider revising it. However, you are the only one who has mentioned it. As for irrelevant, yes, changing it from 40 to 25 is completely irrelevant as the rankings would be absolutely no different. To say we were lazy for leaving it at 40 instead of switching it to 25 is a ridiculous assertion.
So community, is this something that is a game changer for you? Would it make a difference in your game play to have the tribes ranked on a top 10-15 instead of a top 25 that is set?