There is no quick and easy in programming. Even this “little” change, what you´re suggesting, would take weeks or more to develop.
Many don´t know how much work it is to implement even little changes into a game that complex.
Let them focus on the bugs this month, this is and should be #1 on their list.
I would have to disagree. Unless the mechanics and code were so intertwined for those that they are only usable for those specific events they should be set up as more of a executable mod.
They should be able to pull say the bison code, edit it to give it better stats, different drop table and a bigger body.
Save the new bison as epic bison. Drop it into the spawn mechanics and bam.
Granted the world boss should be more unique and this is an oversimplification of the process but it shouldnt be nearly as difficult as you make it out.
The mechanics and code already exsist. Some tweaking and a quick test should be all that’s needed.