Because if we leave emotion out of it what we have here is a car that’s terrifically good at acquiring speed, but much less good at losing it. That actually has too much power for its chassis to deal with (although compared with a G55 it’s a ballet dancer). That returns 17mpg without any semblance of sportiness.
The handling is vague because it weighs 2.6 tonnes before you put anything inside. Add a few family members and you’re looking at three tons heaving along a B-road. You’ll soon learn that you have to tighten the suspension up into Sport or Sport+ just to prop it up through corners that you’ll have had difficulty slowing down for in the first place.