It feels very unnecessary to me that the 8th Guild Bank Tab continues to remain behind the Stay Classy guild achievement - which requires one of every race/class combination at max level in the guild (sans allied races/opposing faction races).
As the leader of a small guild, we use our Guild Bank to share transmogs with each other - and having an 8th tab would greatly assist in keeping the bank organized.
When the achievement/reward was first introduced, both guilds and guild achievements were a much bigger part of the game. Today, players are a lot less incentivized to join a guild - as there is no need for commitment with the ability to join pugs across server for whatever content they’d like whenever they want. In addition, Guild Achievements are more of an afterthought nowadays without any reward.
Even if a guild manages to recruit new members, there’s a very low chance a guild would be able to complete this achievement. For an Alliance guild, you need roughly 65 different race/class combinations. Not only do we know that Alliance races are unfavored among the community due to combat racials, but being able to naturally recruit things like a Pandaren Warlock or Dwarf Mage at max level seems extremely unlikely.
Due to the current feeling of irrelevance for Guild Achievements, and especially the difficulty of a guild completing the Stay Classy achievement where new race/class combinations continue to open up - I propose that the 8th Guild Bank tab just be moved to the guild vendor for purchase.