Their system was derived from ours (in more ways than you know), but their leaderboards are definitely different than ours. They had the advantage of being able to develop with those features in mind from the start, something we didn't have. If we want to match them, then we need to take the necessary steps towards the new system, and that requires a global reset.
I just think it's frustrating that people have clamored for these features, such as Monthly Leaderboards, Regional Leaderboards, and potentially Clan Leaderboards, since seemingly forever. But now that we're in a position to actually add those things that will add lasting appeal to the game, no one wants to take it; they don't want to give up their past in order to build for the future. I get that people don't want to put their effort to waste, and we're offering an option to minimize that loss, but the fact is that such a sacrifice is necessary before we can build something better for us all.
Unfortunately, that still doesn't change the fact that we can't have Regional/Monthly leaderboards without the new system and the resets necessary. Trust us: we've tried quite often to implement those with our current system, since that would be the hypothetical best-case scenario. But the reality of the situation is that that just isn't realistic for us to accomplish.