The popularity of a large fixed blade depends on:
DURABILITY - Whether it can stand heavy duty usage. Not abuse though. That means you can use it to chop materials of reasonable thickness and hardness.
DESIGN - Take a look at popular designs from other companies and ask yourself why these are popular. Most of us are not "field operatives" so we don't have a tendency to go overboard with the knives but we do want a design that says it can stand up to the best chores in our backyard, frontyard or further afield in the sticks.
MATERIAL - Not exotic steels because that would quickly pushes its prices out of ordinary folks' markets. Did someone say "high carbon steel?" Yes, a lot of those popular, affordable ones (large fixed blades) are made of high carbon steel.
BALANCE - Some of those great blades have an inexplicable balance that sort of embraces your hands. When you put one in your right/left hand, the blade feels as if it belongs there. This you can only find out from people in the office, in the street and in the agricultural industry. Meaning, ask people who use large knives a lot.
SHARPNESS - There's nothing like a knife that's sharp and stays sharp for a long time. Nobody likes a knife that is easily blunt and even harder to sharpen. If you can make a large knife that looks tough, stays sharp and has a good balance, you probably have a potential winner in your hands.
AVAILABILITY - Popularity of any product especially a knife also depends on its availability. Most people like to get their choice blades as easily as they buy their bread. It's true. If I want something, I don't want to travel half way across the world to get it, and I want it fast, too.
IN SUMMARY: In conclusion, shall we say a winning blade of the kind which you think may earn Spyderco some hefty profits would be one that is affordable, durable, great design, stays sharp longer, no worries about sharpening, nice sheath (forgot to add this one), reasonable length blade (say, 6.5 inches) and "feel-good" handle, and availability.
All good knives have a market. Expensive blades are for collectors. Functional and practical knives reach out to the masses. Just think of the size of the market. Great volume, low price of item often translates to high profits in the long run. You get repeat customers, too. Customers have a tendency to buy more than one. The extras or spares are for friends and relatives.
