>too expensive to make new molds

See mcfarlane, transformers, and jakks pacific/jazwares. Almost everything coming out is a completely new mold.

>not sell well enough
By legos inflated standards

>lore too confusing
???
Most purchases are not for the lore.

>the real reason
It doesn't sell as well as star wars and ninjago. Therfore its more profitable to just migrate a design team to one of these teams.