But will the flavor be dull without adding one of the cultures with a known flavor profile?
Maybe. It all depends on the bacteriological quality of your milk.
I would make a clabber. Do this. Leave fresh milk out in a waterbath of 80-85 degrees. Like you do for yogurt, but at lower temp. Wait until it coagulates and note how long that takes. Take it out and smell it. It should smell like buttermilk, like a soured kind of milk. If it coagulates quickly, say 6-12 hours, you have enough native bacteria that you don't even need a starter (either one you make or a commercial one). If it takes a long, long time, then you need a starter. If it smells "off", then you need a starter like MA4001 to increase acidity really fast and outcompete the other bacteria.
If it does take a long time, but eventually coagulates in 18-30 hours, you've just made your own homemade starter. Some people call it a clabber. From here, you can either take a few spoonfulls of the starter and reculture it a few generations so it becomes stable, or you can take that clabber and add 1.5% by weight to the raw milk in place of the usual DVI culture. This will give you a more predictable flavor profile.
To sum: try it out on a small batch of milk first and note the time it takes to coagulate, and also note the overall sensory qualities by using your nose and taste buds.
There are more reliable methods of doing all this, but you need a lab.
I personally am against using no added starter for cheesemakers who are starting out. If you're made cheese for a while and have developed natural lactic bacteria ambient to your environment, then it's possible. But even then, it's still easier and more reliable to use clabber as a starter or save whey and use whey as the starter.