It was more difficult to control the runoff speed.
I did not use ball valves on any of the mash tuns or hot liquor backs that built during my the first ten years that I brewed all-grain beer (yes, great beer can be made using humble equipment). Home brewing back then involved more than making beer.
A simple bulkhead assembly can be fashioned out the gasket that is used to seal the valve assembly that comes with the cooler, a 3" section of racking cane, and a number 2-1/2 stopper. The 3" section of racking cane is threaded through the hole in the rubber stopper such that there are roughly equal lengths sticking out of each end of the stopper. The stopper is then inserted though the valve assembly gasket from the inside of the cooler with the smaller end of the stopper pointing towards the outside of the cooler. A length of 5/16ths tubing is pushed onto the outside end of the racking cane, and a house clamp is used to control flow. Believe it or not, one can achieve a fairly snug fit with this arrangement because the liquid is pressing on the larger diameter end of the stopper, which makes the fit even tighter.
With that said, I went all out when I built a new brew house upon returning to the hobby. I used stainless everything. I hated controlling flow with the ball valves so much that I put hose clamps on my lauter tun and hot liquor back hoses. The ball valves are now used only as shutoff valves. All flow rate control is performed using the hose clamps. I like using hose clamps because the flow rate can be adjusted in discrete steps, which makes repeatability much easier.
Here is the 3.5-gallon brewery that I built upon returning to the hobby: