Dick's brain isn't working. The cowl must be too tight.
Gotham doesn't need Bruce Wayne, it needs someone to keep Bruce's legacy going. And if Bruce is declared dead, then who becomes King of Gotham? Oh yeah, Dick Grayson.
He can do the same things Bruce did, support the same charities and philanthropic projects, only he'd not have to worry about Hush screwing things up and trying to ruin them.