This is quite obviously an attempt to cut out the flood of cheap embedded PCs which are ideal for pfSense and steer more sales to their own hardware. Systems such as "The vault" sold by protectli.com are completely adequate for the home network (I am capable of pushing > 100Mbit/s over OpenVPN at ~35% CPU). These run older celeron processors and are dirt cheap.
Hints:
1) The post implies this restriction will only be for the community (free) edition.
"pfSense Community Edition version 2.5 will include a requirement that the CPU supports AES-NI"
2) There is zero reason to require AES-NI, as running with a software fallback will simply yield lower performance. Taking this option away makes no sense unless you want to encourage those who don't pay for software support to buy your hardware, while those already paying for support are free to use their existing gear.