I don't use my laptop outside in the sun. I doubt most people do. Regardless, it's not more expensive...take a look at all the sub-$1000 Windows laptops with OLED then tell me why Apple would probably charge north of $1500 for an OLED laptop?
So many people here who have never, ever owned an OLED laptop seemingly have an opinion on it without never having used one for any period of time needed to cause the issues they think will happen! ASUS, for example, puts up a OLED CARE screen saver after 30 minutes of idle, and Windows lets you hide the taskbar. If Apple were smart, they'd let you hide the menu bar and the taskbar.
I feel people are inventing reasons to diss an OLED when in fact, you can't beat a 3K or 4K 120Hz OLED panel in a laptop for cheap (in Windows).