CanRay and Dave sum up my point nicely. At least in Shadowrun, while some mechanics have changed over the years, other than the leap from the wired to wireless Matrix, there haven't been any major changes that disrupt the feel of the game. Sammies are still sammies, a mage is still a mage, and a hacker still hacks. The core of the game remains the same, and since there is only one 'world' in Shadowrun, the products are a lot more focused than the core D&D products are, and have more depth to them, flavor-wise.
Of course, this is a problem that isn't just seen in RPGs. Back in the day, Nintendo was king, but they got full of themselves, which lead to Sega being a thing, and Playstation after them. Later on, Sony said "We can charge $600 for a console because it is the new Playstation" and people bought the much cheaper X-Box 360 and Wii in droves. Companies get to thinking that because they're the top dawg, they can do anything, and neglect their existing customers.