That is unethical business practice on so many levels.
Firstly, if you are going to supply a cheaply made dongle that is necessary to power an entire suite of products, you should have a facility in the hardware to allow a user to pair a new dongle, when the original fails. It is extremely questionable why this is not an option, it is a very standard thing to offer.
Failing your ability to do that, you should be providing additional dongles with the set, as back ups for when the first one fails.
The inflated amount you charge for this product more than covers the couple of dollars it costs you to manufacture an additional
dongle.
Secondly, are you saying that when the tiny little dongle fails, the only option for a customer is to throw out the entire suite of products? Great option for the environment there Microsoft. Proves that profits are paramount and your environmental footprint is at the bottom of your list of priorities.
Thirdly, this information should be made clear on the product packaging. So unaware customers can make an informed decision about buying an expensive product that relies on one small usb for operation. It should be highlighted that the dongle can and most likely will fail at some point, usually just after the warranty expires, and when that happens the keyboard, mouse and number pad will all be completely useless trash.
Good work Microsoft, always finding new and innovative ways to fleece your customers, while ensuring your tech continues to decline in quality and integrity.