That's now been "fixed" today via a hotfix.
Swipe's threat has been increased by 50%.
Previously the limitation on the number of targets swipe could hit was removed, along with other classes AoE tanking abilities like Thunder Clap.
The immediate effect of this won't be known beyond "it'll let Druids AoE tank better." There might be some backlash from the other classes that Swipe will now cause too much threat compared to their abilities (thus tipping the scale in favor of a Druid tank). There also might be some concern that people will just spam Swipe.
Only time and everyone's reaction will tell.
Thanks to vsureaper for the tip!