I've been total shit at it for 25 years, and I still enjoy it. I've never been good enough to know what I'm missing, though ;-). Is it enough that it's far more fun than running anywhere else, except maybe in the hills? And the craic's good. Just need a beer tent at every event.
Better to have lost your awesome-ness than never to have been awesome at all (especially since you're actually still pretty awesome as semi-permanently injured W40s go). You may want to pick and choose your races a bit more though...somewhere like Tentsmuir does tend to highlight lack of fitness since there isn't too much thinking to do.
I remember a member of the Scottish team at the Senior Home Internationals (last place in team) raising a beer with the immortal quote
"I can give up now and be a has-been, not a never-was"
Many a true word spoken in jest...
I suppose Tentsmuir is just a bit samey, and easy, and I spent a lot of it chasing Gillian down which was a bit tiresome. Anyway, I have only entered the JK and 6-day, so the change of scene might do me good. And my hip+glutes seems to be getting less and less flexible so unless I get some pilates/yoga/stretching done soon, I'm not going to get any better in terrain.