Most people aren't interested in the 'positives' you describe. They go for the game, and generally discover the standard of both play and facilities is rubbish. Non-league football isn't particularly cheap, either, certainly not for families. One of my brothers, an infrequent football attender, home for the weekend to visit the folks, went to the Halifax-Boreham Wood match yesterday, and was astonished to discover he had to pay twenty quid. For me, a lot of non-league football's charm has gone because the standard of behaviour on the field and in the technical areas is as appalling as in the Premier and Football leagues. Frankly, if all non-league football were free, its audience wouldn't increase markedly. The overwhelming majority know what non-league football is, and choose to ignore it. My brother (who, incidentally, had no idea it was Non-League Day) certainly didn't regard his brief encounter as a value for money experience.
Non league football needs to offer something different. Part of the appeal of non league football is "you can stand and have a pint watching the match". Only at step 1 you can't, at a lot of other grounds, particularly in step 2, you can't. FA Competitions - you can't. So that does turn people off.
Another big appeal is price, yet you're paying the best part of 20 quid at step 1 and around 15 quid at step 2. That's not exactly cheap. So if you pay the best part of 20 quid for a ticket and can't have a pint during the match, then straight away you're losing 2 key selling points to potential fans.
It's always important to get kids in but at younger ages they aren't interested as much in watching the game as running about and being kids. It's teenagers, students and early 20s kids clubs who you really need to be wooing with prices etc and the key demographic to getting more of an atmosphrere going and building a buzz that way and get them in the habbit of live forever rather than lost to it for Soccer Saturday or the pub.
Kids under 10 go free - great, but they aren't going to watch the match anyway.