Only to be different. Let's face it, before the XK, Jaguar was a wannabe Bentley even then. The Mk2 saloon almost made the grade, but the E Type put Jaguar right up there, because the design and engineering was spot on. They never managed to repeat that success, because even then it was bigger and lardier. The XJ6 was a great car dynamically. I borrowed one for my wedding car and it was super impressive.
It's sad because even with the Le Mans success, the glow of that era was soon forgotten. And I doubt many of the pinkies at Jaguar even know.