I was right again

For this one film, he acted in a mentor role. And not a very good one. It was to serve as a counterpart to Toomes: Tony's a good guy but a crappy "dad" whereas Toomes is a bad guy but a good parent.

They did mention Ben though, Peter says he didn't want May to know because she's "been through so much". That was a reference to Ben. They just didn't directly mention him because it's been done too often in the prior adaptations. They WILL reference him later, but wanted to do something different this time around.

Besides, it isn't like Begins didn't do something similar with them making Ra's more of a "father" figure to Bruce than he was in the comics.