Routers keep improving. The majority of both business and home users rarely change their internet equipment. After 3 years you may not only be behind in the technology but others around you may be making your connectivity worse. What is there to gain from looking at your router and your modem?
You can increase transfer speed. You can decrease your latency(the lag that all transfers have.) You can maintain a stable signal at higher bandwidth, fast is no good if it keeps stuttering up and down. You can support many data streams simultaneously without degradation.
All of these are important because we have more devices, a more crowded wireless bandwidth, and we have greater traffic. It’s just the normal advance of technology. Today, the latest capabilities of routers are mesh networked and are expanding into newly freed 6GHz frequencies. The labeling of this is WIFI 6E.
But do you need it? It depends. These latest features are expensive and they’re new. So only in the most demanding situations should you consider purchasing them. In the meantime, consider buying a WiFI 5 mesh network for less than half the cost.
I’ll recommend one other feature. Purchase a system that uses your secure account, like a GMail account to log in and manage it. Make sure that it does automatic firmware updates so you will always have the latest updates. Virtually all older routers are hackable and many have never had their admin password changed or updated firmware. This is just an open door waiting for any and all to walk through.
My recommendation is a system like Google’s Nest wifi, Orbi or Eero owned by Amazon. Since they update themselves you can get them setup and running and mostly ignore them(like you do now but at your peril.) Stay away from off brands and consider US or EU brands to prevent future problems.
WiFi 6 and 6E will become more widely used in a few years and their routers will be cheaper. Check back in 3 years and see what is new and what is good enough.