If your diabetes behaves, if you don't get many hypos or highs, then you may just have developed an eye for 'I can eat this amount of this stuff with my insulin' and that's all good.
What I do is that one day I may want to eat something entirely different from the previous day in which case I will need a different amount of insulin - and that dose change will depend on... the amount of carbohydrate in what I am about to eat.
It's not wrong to not do it. What would be wrong was if what you were already doing was not working. It seems to be, generally.
However, carb counting is not that hard generally, so if you do want to at least know what it is, do ask and someone will point you in the right direction.
For me, it gives me more flexibility. That's basically it. That and it helps me control my levels better. That's the way I prefer things. Personal choice as long as the result is in range, and it seems to be.
-M