by Ken Davis » Tue Feb 10, 2015 10:46 pm
My guess is because it's known he's going to appear at some point, they'll ease him and his presence in in steps.
Might start with a off-hand comment about a " Spider-guy, in New York City"---maybe from Coulson on Agent's of SHIELD, and then maybe an end-credit scene in one of the movies before Civil War, and then an appearance in Civil war itself, with a segue into his own next film.
I'd bet dollars to donuts now that in-jokes and sight gags for Spidey, the Daily Bugle et al will start appearing soon, because those things, as much as character appearances, place him in the Universe at large. A quick conversion of a building on the background to an Oscorp tower and boom, instant placement, and the tapestry starts weaving.