I dunno why, most design jobs have offices full of imacs. They’re the machine that makes the most sense for work places.It's clearly not going to be a big seller, but then no Mac desktop family has been for at least a decade, if not more. The iMac family is likely the best-selling Mac desktop, but it probably equals 10-15% of all Mac sales, at best.
So that Apple chooses not to update any of the desktop line annually should not be surprising.