I have 2 ideas, but unfortunately, they're more about changing parts of the game than it is just adding classes - and sadly the cost of which ends up at the club level.
Last time I got into threads like this, I did some (admittedly basic somewhat anecdotal) market research. Between classifieds, and airgun marketplaces that cater to the general airgun community - there are more .22 options available in multiple price tiers than there are in sub-20 (generally .177). Given other posts about increasing popularity of some other higher power sports, and American general 'more power' sentiment - I'd suspect that the vast majority of mid-tier non-Walmart style break-barrel rifles sold are above 20fpe, likely .22. If you just got your new rifle from Pyramyd and want to check out a fun game -- there's a good chance you're over the FPE limit and can't play without buying another gun.
Option 1 is the targets change to meet the needs of the American market. That means replacing a bunch of targets made with metal not designed to get pulverized by high powered rifles. I think there can/should still be an upper limit so people arent out there with an Airforce Texan. That's a cost that is (very understandably) hard to toss out there to a club...probably a few thousand dollars. I dont have the engineering background, but I'd also assume those new targets would end up too heavy and cause some issues with WFTF sub-12 not able to knock em down, so it's a consideration as to why it's not a 'great' idea, but it is AN idea.
Option 2 is setting out a few more easier targets (how many I dont know) just for newer shooters. Lets face it - as high end guns are becoming laser beams, MDs have to keep stretching the limits of the rules on KZ sizes, distances, and positioning to keep the great shooters from consistently cleaning courses and being bored and not showing up to matches. The harder it is for a 15 year pro with a Thomas, the EXPONENTIALLY harder it will ever be for a second year shooter with an Avenger. To keep the golf analogy going - there's ladies/kids tee boxes to make it a little easier. They're not competing in the same class as men's pro. On a lane with a stupid high troyer target, toss in a very reasonable one that noob class replaces that shot with. They're not competing with the experts. Yes, it means clubs have to buy some additional targes AND have to think about course design and manpower with setup. Not an ideal solution, but having 5-8 extra targets in the rotation is a far bit cheaper than replacing 30 or 40 with better steel.
I'm not saying I have the perfect (or even correct) idea. I do think, if we want to get people in, we need to it more accessible to the average person. We need it to be FUN to participate - and ultimately that means the thrill of knocking down enough targets to make it feel like you had a good time on the course, got your money's worth of fun, and didnt waste a day missing 95% of the shots. What that number is - probably need some time and research. Either way, whatever means a good experience for new shooters without making it too boring and easy for the hardcore competitors.
WHat we dont need is people who already own the kit pulling the ladder up behind them and telling new people to pony up a mortgage payment or two or 'learn to suffer through the bad scores' until they can play with the big kids.