If there's one vital, important, quintessential thing that Overwatch needs, it has to be the (future) implementation of community made content. I'll bee quick and just list some of its benefits.
#1: It promotes positive participation in the community, a chance for some to actively contribute to the game.
#4: More content is being added to the game. Maps, sprays, skins, taunts, maybe even heroes and then some. There is a innumerable amount of content that can be added to the game by the community.
#3: Content is added to the game for free at the same time it lessens the overall workload on the devs.
#5: (This is merely a suggestion) Rewards for competitive play could be generated by the community, for the community.
#6: There are no negative aspects to the addition of community made content being added to the official game.

The list goes on.

We would like to continue to explore ways of allowing the community to contribute content to Overwatch. Overwatch is a brand new engine so it's going to take awhile for us to achieve that vision.

Blizzard has a rich history of supporting community made content. From the Warcraft and Starcraft editors to World of Warcraft's thriving UI mod community, we have some really great examples of our passion for community made content. The whole MOBA genre exists because of our support for the mod community!

Overwatch now features the Custom Game Workshop, which is a script based editing system to further customize and create unique game modes for Overwatch.

There is still currently no timetable for a map editor in Overwatch.