As a runner with no ambition to race - any reason to incorporate tempo runs?

I have been running quite consistently for over two years now, currently averaging about 4 runs a week with a total of 40~50km of total distance.

I started my running journey following training plans that included a variety of different runs, including interval runs, negative splits, high cadence, tempo runs, you name it. Basically starting with C25K programmes, and following Garmin training plans after this. This would cause me injuries from time to time, and I would often take breaks to recover and restart the training plans.

I never had a goal apart from enjoying my runs, getting the nice mental benefits, and burning some calories while I was at it. And as a result, over the past year I have increasingly moved away from training plans and gravitated towards simply doing 4 long runs every week at a comfortable pace, usually 10KM at an aerobic heart rate. I have not had a single injury since starting running like this.

However, I keep seeing people talk about the necessity of tempo runs and the benefits they provide. My question is simple, as someone who has zero aspirations to join a race, who simply wants to enjoy running long distances, but who does enjoy challenging himself to run longer distances quicker, how valuable is it to incorporate tempo runs in my plan?

I did a tempo run recently, and immediately felt that my achilleas heel was not happy about it, making me lean towards just stopping tempo runs overall. Any insights you may have are most welcome!