The WR-250R (and WR-250X) come stock with ultra-tall geariing via a 43-tooth (42 on the X) rear sprocket.
The 13-tooth front is normal enough.
This is to pass drive-by noise tests that must be met before the bike is produced.
It's not to make the bike great on the freeway.
A typical 250cc 4-stroke off-road bike will come with a rear sprocket of around 48 teeth, at least.
Besides a fuel programmer, gearing the bike down to something realistic will make things better, not to mention off-road-worthy tires.
A reality of doing wheelies or unweighting the front of the bike dramatically on a 250cc off-road bike with this amount of power on tap is to get your butt toward the back of the seat.
That's why you see such long seats on dirt bikes, not for carrying passengers.
Speaking of the seat, this is why dirt bikes have tallish seat heights, too - to keep enough distance from seat to footpegs and to avoid your legs being folded-up so much that you couldn't make such a quick maneuver while riding the bike.
Riding the bike fast off-road means getting physical because the terrain is not smooth.