That 5 mph might not matter in small States where you look at trips in terms of miles but in Texas we use "how many hours".
A trip across Texas is 14 hours.That 5 mph increase knocks an hour off that trip.
That is why they increased the limit.
By the end of that trip you feel like you were born,raised and died of old age on the road.....and you haven't even crossed the damn border yet.
FWIW It's 900 miles across Texas.