I have a Master Touch from a few years back and the thermometer is at 90 degrees to the vent. Works much better. The dome temp is usually 20C higher so it's an easy way to know what the kettle is doing.
The first years of the 26.75" kettles (2008-2010??) had the same 90 degree placement. Mine is from a few years later and it has the 180 degree placement. Doesn't bother me.
Useless? I think not. I always put the therm over the meat being cooked. I realize that lid temp and grate are not the same. It's more of a reference point for me. I know what's going on with my fire and I know how to cook. I can take it from there...
The kettle never struck me as a cooker that i am trying to keep perfect temp. That done thermo is just so you know when the fire is getting out of hand.