Yeah it was so popular they even released a specific WRT54GL model (where the L stands for Linux) in order to keep supporting third-party firmware after the main hardware series moved on to a more optimized VxWorks-based OS that let them ship less RAM and Flash.

A mainstream hardware company releasing a specific product SKU to support third party firmware really sounds crazy from the perspective of the current market where a substantial portion of the value in selling hardware is supposed to come from subscriptions and surveillance.