It is hard to do these things, especially on a voluntary basis, and they sometimes just do have a 'life-cycle'.
I used to do fairly large outdoor events at various stately homes - car rallies. The number of people who would actually turn up and do something, both before and during the event would steadily drop over time and it eventually became clear that we (that were left) just couldn't do it all ourselves, even though we got better and more efficient. If you're wise enough, you will stop before it all falls to pieces on the day...
The events get bigger and the active personnel dwindle.
After the Covid disruption, Stafford has drifted back into the autumn and may take up some of the slack, but it's generally fairly full anyway. For people arriving by road, it's probably better, and they run a bus from the station, but it's nowhere near as convenient as the NEC for the rail-borne visitor.
Trade vehicle access to the halls may be less convenient than the NEC, but it's not too bad.