User blog comment:Zathronas/Speculative author: Where are the Grimm?/@comment-9464517-20140914093355/@comment-24218038-20140914115948

Never said all of them would. Some of them could.

What build-up? Beside Velvet, the others were only announced. Establishing characters for death is good if the purpose is to make an emotional impact. The reason for their deaths here is to establish the Grimm as legitimate threat. Killing Beacon students is enough.

Same thing happened with Mercury and Emerald. To legitimize the two as threat, Monty had them kill Tukson.