Citation

As Lifehacker put it way back in 2006, it was the perfect way to turn your 60ドル router into a 600ドル router, which likely meant it was potentially costing Cisco money to have a device this good on the market.

So as a result, the company "upgraded" the router in a way that was effectively a downgrade, removing the Linux-based firmware, replacing it with a proprietary equivalent, and cutting down the amount of RAM and storage the device used, which made it difficult to replace the firmware with something created by a third party. This angered end users, and Cisco (apparently realizing it had screwed up) eventually released a Linux version of the router, the WRT54GL, which restored the specifications removed.