I'm here to present an explanation as to why the Teen Titans would be a perfect addition to the Arrowverse (Arrow, The Flash, Vixen, Supergirl, Legends of Tomorrow).....so let's begin:
1. It would confirm 100% that Batman exists in the Arrowverse:
Even though Batman does exist in the Arrowverse, we are still yet uncertain as there has never been a line explicitly saying that The Caped Crusader is protecting Gotham with his allies even if he is, and the reason Titans would confirm that....
The Boy Wonder Dick Grayson has always been a great part of the Batman mythos, and the script going around reportedly has him set as he just left Batman's shadow and leaves Gotham to protect Blüdhaven alongside wheelchair bound Barbara Gordon, with the help of superhero duo Hawk and Dove, with the plan to introduce Starfire and Raven later, the reason he would be an incredible addition is that he would represent a connection to Batman, and subsequently confirm that he has been protecting his city all along while Oliver, Barry and their teams were protecting theirs. Which leads us to the next point...
Crossovers, ah, what a dream, first only non-continious Flash/Arrow team-ups, to the Supergirl/Flash crossover that are setting up future crossovers and tell more stories. How cool would it be too see the lighthearted Kara and Cisco..........react to Robin employing Batman's method of chiping people's teeth to get information? Probably not so well, but it would be super awesome to see this usually lighthearted personalities like Felicity or Vixen interact with the serious, no-fun Dick and Babs...still awesome, plus, who wouldn't love seeing this scene?
*Team walks into S.T.A.R Labs
Cisco: So, here are our computers
Barry: There's my suit
Starfire: Looks pretty
Mari: Wow this is awesome
Oliver: Something wrong Dick?
Robin: No, it's just.......the Bat-computer is better
4. It would re-define all of the characters
One of the most important reasons this would be a great addition is that it would shed some new light on these characters who are not well known or liked by the general audience, give for example Robin:
When we think about Robin:
-Has the respect of Batman
-Even became Batman for awhile
-Stepped away and became his own hero
-One of the deepest most interesting characters in comics
When the general audience thinks about Robin:
-Chris O' Donnell's bat-nipples