You have a little red swirly beam waiting for you once you solo GR70 first time. 
And yeah, it’s pretty rare that rerolling damage range is the best option on a weapon.
The game kindof leads you to think that + % physical damage (on bracers for example) would synergise with having physical type weapon damage range, but the element of the attack is actually determined by the skill and the rune. So it’s a common mistake that people reroll the range to match the weapons damage type to their elemental damage rolls on other pieces, and I think that’s what happened here. Just another poorly documented mechanic in diablo 3.