Regarding our entry into WW1, to be fair, it was unrestricted U-boat warfare and mainly the Zimmerman telegram; OTT I agree Wilson was not a nice person.
Because Britain had a naval blockade against Germany. A true neutral would have told Britain, that we wouldn't ship anything to them and risk our ships while they were blockading Germany.
Much like the U.S. attacked Cambodia to cut off supply lines to the Viet Cong.
Attacking the enemy's supply lines (even while that supply line is outside enemy territory) is a standard practice in war.