The fact that BIOS/DRAC/RAID initialisation is slow on some servers is irrelevant. Linux's init and the firmware initialisation don't run concurrently, therefore if init takes longer the whole boot takes longer. Additionally many servers manufacturers have improved boot times in the last few years (down from 10+ minutes, to 5+ minutes, to less).
Most routers don't take as long to boot as you claim. The entire OS is about 8 MB (uncompressed) and RAM is only 32 MB, and the medium that the OS is stored on is faster than a computer's hard drive. So just looking at IO should tell you your supposition is flawed. In my experience most Linux based routers boot the RJ-45 interface (LAN side) in under 20 seconds unless it is allocating slowly on the WAN interface (e.g. unable to get an IP, etc). If you set a static WAN IP/gateway/etc, then boot times comes down substantially.
Additionally the whole concept that every time your PC turns off you'll also turn off your router at the mains is, uhh, strange. Sure there are power cuts but that isn't the only time you shutdown your PC throughout the year.
The concept that your PC needs to wait for the server is equally flawed. Again, yes, power cuts. But PCs get shut down significantly more often than servers and if we're playing that game then wouldn't a "server" have a UPS anyway?
So overall your argument for why boot times don't matter lacks any kind of substance. It is also purely based on a PC->Server->Router infrastructure where nothing is on a UPS and everything suffers from a power cut (then "races" to all come back up).
In the real world my phone has Linux, our "Tivo" has Linux, our printer has Linux, our car's entertainment system has Linux, etc. So bad Linux boot times will be noticed day to day. It matters to a lot of people and while I don't know if systemd is the solution, I do know that progress is needed relative to the classic UNIX init system (per the article).
