If you're simply taking someone else's design you should at the very least pay them a royalty for doing so.
Intellectual Property, which includes design, theft is well, er...theft isn't it?
How would any of us feel if we'd written a song and someone else stole it?
Dingwall clearly know that they are bang to rights here and have been 'getting away with it' for too long, otherwise they wouldn't have made the above changes sharpish would they?
Aria, Yamaha etc have all come up with their own designs and made a great success of the their bass ranges over many decades without simply plagiarising Fender's designs.
But as Chris rightly says, unless Gibson get their act together just pursuing copycats alone isn't going to save their brand.