Consider also, that Stratasys had no answer to their biggest competitor's (3DSystems) consumer line that's been going gangbusters (Cubify).
I can imagine a world where $403M worth of stock is a good trade for a well-known name, a product line with a large customer base, and profitable consumer sub-unit to compete your biggest competitor, who has the same when you don't.
edit: actually I forgot to do the math. if they sold $44M of stuff already, 10x that for an obviously growing business is a pretty typical exit