World of Warcraft's recent Update 7.3.5 has brought Legion's level scaling system to every single zone across all of the expansions. So if you ever wanted to level a new character and explore some of the regions you haven't touched since the Cataclysm, now would be a very good time to do so. 

If that isn't enough of an incentive to start up a new character, you might also be interested to hear that the pre-order for the Battle for Azeroth expansion has recently gone live, and with it the ability to play as one of the new Allied Races. The full version will feature six races in total, while right now you can only play as the Void Elves, Highmountain Tauren, Nightborne and Lightforged Draenei. There are also a bunch of additional benefits if you decide to go with the more expensive "Digital Deluxe" edition, but it's pretty much all cosmetic fluff so if you're just in it for the gameplay I wouldn't worry too much about it. That said, here's what the new races look like:

The Alliance allied races - Dark Iron Dwarves are currently not playable

The Horde allied races - Zandalari Trolls are currently not playable

Before you decide whether you want to pre-order or not, it is important to mention that Battle for Azeroth won't be releasing any time soon. According to the latest announcement we're going to have to wait until September 21st (or potentially a bit sooner) to explore all of the new content. So if you aren't playing WoW right now it might be prudent to wait a few more months before springing for your wallet, just to make sure you don't burn out by the time Battle for Azeroth arrives.

You can learn more about Battle for Azeroth, as well as the various allied races, by heading over to the official website. And finally, here's a brief developer guide showing off how to unlock the new races. Have fun!