Why charge less? To sell product.
The Marshall brand is stagnant. Simply too many companies out there in this price range that do the job better and everyone knows this. Bring those in at 1.5k cheaper and reset the market for modded Marshalls. That puts a dent in the competition, that claws back some of your market space.
Not only that it gives them room to grow in the future with more mods and products. You're basically topped out right out of the gate, zero room to grow. I mean let's say they added more bells and whistles and suddenly the next amp is 4.5k, anyone buying that? Nope, might as well get a Wizard at that point.
I mean they essentially priced themselves out of the very market they are trying to recapture.