Not to re-hash what's been said, but if you want to open up sailing to more people who aren't doing it now, don't build another flavor of the same sport boat that's saturated the market. If J/70s are selling like hotcakes, kill the rest of the sport boats and support that class. Looking for another way to dillute it is just perpetuating the failure formula.
If you want something to bring a different crowed in, build a true family racer/cruiser that has something in it for both spouses and the kids. Even if you can afford it, it's awefully hard to convince a spouse to buy a boat he/she isn't even going to be able to enjoy.
Here's a design brief:
* Large enough to sleep four in relative comfort in truly separated compartments
* Plumbed head in a separate compartment (head only, no sink, no shower, no vanity, just a head, toilet paper roll holder and enough room to stand up and turn around, and not in the v-berth for crying out loud, not open to the rest of the cabin or the forward stateroom).
* small inboard diesel.
* nice looking.
* big enough rig to provide some performance, but small enough not to intimidate the non hard-core spouse and a pre-teen kid or two.
* enough rig sensitivity to keep a 'mature' dinghy sailor content, but not so complicated that it requires constant attention.
* enough stability not to intimidate the non hard-core spouse and a pre-teen kid or two, enough stability not to require a pack of rail meat just to stay upright while casually racing in moderate conditions.
* Big enough cockpit to cocktail cruise four to six (this may be tough to accomdate in a 30'er that sleeps four and has a separate head, tiller sweep is an issue). Make sure there is decent back support for a three hour tour.
* Simple and forgiving enough that the speed differences between boats are small, makes racing closer in casual fleets and maximizes chances that everyone in the fleet has a taste of success
* Don't simplify the rig so much that you only have jobs for one or two people and everyone else is left out of the fun most of the time, but keep it simple enough that you can race the boat casually with varying crew sizes.
* nice looking (did I mention that before). Make it look like a boat, not a toy.
* simple galley surfaces, enough storage for plates and utinsels for six and cocktail containers for eight, sink with cold running water.
* simple electrical system, cabin lights, instruments and running/anchor lights.
* Hanging locker with space for a family of four's foulies.
* standing headroom for a 6'2" owner
* simple and durable construction
* minimize unnecessary clutter, gadgets and complication, focus on build quality, durability and ease of maintenance over the long term. People don't take small sailboats cruising for weeks on end, but they do take them one or two nights out. Keep it easy to stock with ice, bottled water, food that doesn't need cooking and avoid built in things that will cost money and break.
* a way to make coffee (yes, this arguably violates some of the other factors, but don't discount its importance)
* target a cost between $100 and $150k (this seems reasonable to me for a nice looking useful and fun family racer cruiser).
People used to make boats like this back in the 60s, 70s and early 80s, they even sold a couple. To me, 30' is about the ideal size, the slips are reasonable, things charged by the foot (winter storage, bottom paint, hauling, detailing, etc.) are relatively affordable, and it's small enough for one experienced family member to handle alone around the docks without much drama while the rest of the family/cocktail party enjoy themselves.
Just my 2 cents.