Everyone wants "cheap"
Trouble is everyone wants "cheap" or "free" routers. I have clients who get upset if I tell them a router is over £100 so instead they end up with sub-£40 devices. Devices that attempt to be routers, modems, wireless AP, print servers, USB Backups, make the tea whilst juggling three balls in the air.
Not surprising these cheap bits of kit keep failing. Is there any profit in these silly devices? At this end of the market I can see why support is a PITA. If they have to chase a firmware update out of the manufacturer they must burn that profit away.
It is also noticeable that even among the trusted brand names the exact same router is sold at the bottom end just with a different logo in the corner of the control panels. I get a feeling some of these companies build their own expensive kit, but bring in cheaper stuff to fill in the holes at the bottom end of the market.
The only reason everyone is now noticing these security issues is because finally people are actually *looking* for the problems. These issues have always been there, but now we have companies who make money shouting about it.