Sorry, lame argument to compare two different industries.
The electronics industry led the consumer to get used with a different process: The hardware and the software are two different parts of the product. The marketing pressure makes the hardware engineering department to get the hardware PLATFORM ready ASAP an then the product is released, bugs and all. Then, with the product on the market, the software engineers start to collect market feedback (exactly what is going on here) and decide to fix the outstanding bugs and to drive the system (hardware + software) to what the market asks.
If industries thought like you, you would still be using the Windows XP released in 2001 or whatever other obsolete OS.
Manufacturers have a RESPONSABILITY with the consumers, especially because Garmin expects we continue to buy their maps and stuff.
Besides, the market is a moving target and Garmin cannot launch a new, monolithic product, everytime they want to compete. They have to iterate their current platform and drive it to the better response, it makes much more sense from an economic point of view.