Why don't the A380 and A350 have trim wheels?
(Source)

Both the A350 and A380 have alternate pitch trim control rocker aft of the flap lever in the cockpit to replace the pitch trim wheels near the throttle quadrant.

OPINION: I'd guess this was done simply in a continuous effort to improve the flight deck, reduce clutter and reduce weight. As a pilot myself, I’m not thrilled with it from a kinesthetic standpoint, as the wheel is much more natural to use.