"Hogwarts is full of people who'd find it awesome if Harry Potter gave them some of his personal attention."

Harry has given lots of people his personal attention, which he justified by the fact it would help them -- Neville, whom he pranked, Padma Patil, whom he pranked, Gregory Goyle, whom he pranked, Lesath Lestrange who he pranked others for... Even his own past self he pranked.

So why not Hagrid? I don't see this really being about Harry time-budgeting, it's more about the fact that he can't be simply nice to people -- McGonnaggal would likely have achieved better results if she had asked Harry to devise an elaborate prank that would have dubiously potentially helped Hagrid in some ambiguous way.