I would agree with your statistics since 79.6% of Statistics are made up.And the reason they're not interested is because only a tiny minority of players even bother with GvG. It makes no economic sense to waste resources updating/upgrading a feature that is ignored by over 95% of active players and unavailable on the most used platform.
On the other hand most players use mobile devices (my statistics surmise 81.3%) so they have no access or probably even awareness of GvG.
Yet, it is still used as a generator (massive) of prestige affecting Guild abilities.
Plus, IMHO, it is a great social interaction venue within a Guild.
Yes I know INNO is probably not interested, but they should be. If you abandon minimize long time players, you'll end up with short timers.....