The price difference between something with Cortex-A55 64-bit cores and something with obsolete 32-bit cores is negligible. For modern home routers or security

The price difference between something with Cortex-A55 64-bit cores and something with obsolete 32-bit cores is negligible. For modern home routers or security appliances you want them to be able to easily execute firewalls with complex sets of rules at multi-gigabit per second throughput, so that the router throughput should not be limited by the CPU instead of the Ethernet or WiFi interfaces. For this, you really need something like Cortex-A55. The routers with obsolete CPUs limit the performance without any worthwhile price reduction. On the other hand, for many embedded projects where a 32-bit CPU is the right choice, the developers choose Linux just because they are familiar with it and they are too lazy to read the manuals of some free real-time operating system, even if in fact the latter might require less development work and maintenance work for their software project.