It is not compulsory to fit XL tyres to an xc90 but more of a personal choice and for the few extra pennies involved is common sense to me.
It certainly improves the ride and control of this big comfortable beast
It was because of the state of the roads in ill repair nowadays that persuaded me to buy an xc90.
I was fed up keep paying out for damaged suspension components and burst tyres.
It helps protect against side wall damage when entering and exiting potholes which very often you don't see until it's too late.

It helps prevent damage when parallel parking in a tight spot and accidental kerbing sometimes.

And last but not least there is a tendency for newly resurfaced roads today to be a couple of inches above original level but the surface water gully gratings never get raised so the gully then acts the same as entering and exiting a pothole.

Went with Goodyear Efficient Grip 2 SUV in the end. They are the 107 XL ones (I have only ever run 103s) and, blimey, what a difference. They just feel so much more stable and responsive, even with a knackered ball joint (being fixed tomorrow)!

Glad you notice the difference...people just don't realise what a difference it makes...try them on 39psi and they should go where you aim them and last you for ages(that is the recommended eco setting for the XC90)
Enjoy.

I have these on my xc90 and find them to be excellent tires.