AFR is going to directly effect your EGTs as you know. The leaner the cylinder mixture the higher your EGTs will be, continues going up if you go even more lean than stoichiometric. One of the major functions of the fuel beyond creating the combustion event is keeping cylinder temperatures down. This is also key in preventing knock or detonation, which is why AFR is so important. EGT monitoring would just be icing on the cake in my opinion.
I've never had EGTs on anything personally, I know they definitely have their place but I feel like it's for those trying to gain that last 1 or 2% or just absurdly high hp cars where everything becomes even more critical.