I think Samsung might be doing themselves a disservice by not releasing JB on the Galaxy Tab 10.1. Android, and in particular Samsung have a reputation of having infrequent update cycles and short support periods. iOS and iDevices (and Nexus devices for that matter) are much more likely to have frequent updates with longer support periods.
That can be said of all manufacturers that put a UI overlay on top of Android, like HTC, Motorola, etc. It takes a fair bit of time and work to come up with the overlay, program it, test it for feedback and bugs, then release it. All this is done after the source for the new version is released to the manufacturers, so of course it takes a while. And the more updates they release, the more work required with little financial gain. It doesn't make financial sense to keep spending money on updating products that have been replaced with newer models/versions.
When I went shopping for a tablet, I wanted one that was sleek, light, good screen, good battery life, 3G data, plenty of accessories, and have a good UI. The Tab 10.1 was the only viable option at the time. Today it's still one of the better options, although newer models are more appealing.
As for Apple devices, they offer updates for longer periods. But it's not to satisfy customers. Its purpose is to alter the user experience with bigger and heavier code in order to convince users to upgrade to the newer hardware to support the new firmware. Look at the release cycle of firmware and hardware...there's a clear pattern of firmware updates that add some new features (but not all), and new hardware to run the new firmware. It's a way to get repeat business without making it look obvious. And clearly it works for the masses of Apple users.
As for a disservice, I don't think so. The orginal Tab 10.1 is not manufactured anymore as it has been replaced with the Tab 2. That device, or the Note 10.1 is the flagship tablet for Samsung and that's where they will apply updates and marketing as expected. If someone asks if the original Tab 10.1 is still a good purchase, I'd tell them 'it is if it does what they want at the price point'.