1. Wifi routers are very complicated. You need smart people at all levels of the stack to build a modern wifi router. You need people who know 802.1ac like the back side of their hand, people who know how to set up and deploy linux environments, embedded engineers for debugging OEM driver issues, networking gurus for handling the voodoo in levels 2-4 of the OSI stack, application people for rolling the user interface, cloud people for cloud support. Normally this isn't a big deal, if it wasnt for the next point
2. The profit margins on consumer routers are complete trash. Even if you're one of the big boys with double digit market share, you're going to have a very hard time keeping a decent engineering team staffed and your marketing team staffed at the same time while still breaking even.
3. Consumer router sales are SKU driven. There are dozens of price and performance points you have to hit to meet the demands of the consumer market. You cannot make be profitable with less than 10 actively selling SKUs. Every time you release a new SKU, it's a new opportunity for marketing to try to sell the device to brick and mortar stores that they're trying to expand into. If you aren't releasing 5-6 SKUs each year, you're going to have a very hard time keeping your router on store shelves.
4. Since sales are SKU driven and your engineering team is probably under funded, you have the exciting problem of maintenance releases. If your company has 50 supported SKUs and you find a non-driver issue in one of them, the chances are that it affects 10 other SKUs as well, if not all of your other SKUs. Pushing that maintenance firmware to 50 SKUs could easily take 6 months of combined QA or Firmware development time. As far as your marketing department is concerned, all that time you spend on maintenance releases is time that isn't spent on making new SKUs with exciting new features.
tldr: get a business class wifi router