That's because the K1600 really is the greatest bike most of its riders have ever owned!
Honestly, there were some early issues with leaky water pumps, flaky handlebar switch gear, and fast-wearing rear brake pads, but that's all been pretty well sorted by now.
And yes, the factory Bluetooth is merely adequate, which really stands out poorly when the rest of the machine is so well-executed. But there are some decent aftermarket solutions available, depending on your own preferences for features, fidelity, and cost.
Now every Beemer I've ever owned has had a custom seat and windshield and the K16 is no exception, although many riders are fine with the stock offerings.
Most of the aftermarket parts that K16 owners buy are for comfort customization, convenience, or additional safety.
And tires. Lots of tires, as you explore the impressive capabilities of this incredible Sport-Touring machine . . .
BMW really does have the K16 pretty well sorted at this point.