It's a lot of money to spend on a one-gate airport. I know it won't happen but some direct flights to farther places would make it a lot more appealing.
As a family of four, there is no cost savings. The flights are usually $200-300 RT and with four of us that equals $900-1200 in additional cost. Sure, there is drive time and, sure, there are parking fees but I can save $800+ by not flying out of ACT compared to DFW or Austin.
Then throw in the limitations on flight times. They usually have a really early AM flight time (I think around 5:30A) that gives you flex but if you are trying to catch a flight out of DFW between late morning to noon, you are forced into waking up at 4AM to leave ACT at 5:30 and then spending 5+ hours at DFW. Or...you could wake up at 7AM, leave Waco at 8AM and be at DFW in time for a noon flight. Easier that way.
Making sure you make the connecting flight on the way back to ACT can be a challenge at times as well if there are delays.
Why would I pay $800+ for the inconvenience?
Now, if I were a couple or a single traveling, that might change things. Waco needs it for those that regularly travel for business and don't want to constantly make the drive but it just doesn't make much sense for the average Wacoan.
That said, I think I would spend the extra money if there were a direct flight from ACT to, say, Denver but I can't imagine there is any demand for a regularly scheduled leg like that.