Art has always been a big part of D&D, especially in the later editions. Why would you lay off an art director to balance the books?
Game design and adventure design have also always been a big part of D&D, but those folks get laid off pretty regularly.
You might lay off an art director that's been around a while to pull in a new one at a lower salary, for example.
WoTc is owned by a major corporation, let's not pretend that all people that get let go are faultless.
The second part of that sentence does not seem to follow form the first. How does WotC being owned by a major corporation imply anything about fault in individual employees?
I don't pretend that all people that get let go are faultless. But, *given* the history, the financial explanation seems like the thing to look at first.
Though, Piratecat's note seems even more likely, still. A new upper management often leads to replacements lower down the chain, regardless of personal performance.