I only throw it out there for reference. Weight seems to come into play for a lot of things related to bikes. The stock suspension on the Tiger 1050, for example, gets a few complaints on the Tiger forum for being too soft (bottoming out) for 2-up riding. After gathering some data (because I asked), it boils down to folks either not properly adjusting the suspension (Tiger is fully adjustable front and back) for their size (or riding 2-up) or they're exceeding the weight limitations of the bike when they add a pillion rider and/or luggage. It's hardly a deficiency with the bike if it has a weight limit of 550 lbs (don't know if that's the limit; just an example) and you choose to load the bike down with 600 lbs.
Back on topic of the Rocket seats, I've never had an issue with the Triumph seats, but a lot of folks on the forum complain they're too soft. I have to assume that's because they're packing a few more donuts than I am.