IMO, the "unnecessary" comments can be justified. There's always going to be a bit of an uphill battle with reboots. Especially one that came so soon after the first series. The film should able to convey the importance/meaning/rationale behind the reboot (other than studio business) through a truly unique vision, fantastic performances, and a well crafted story, etc. For film critics, a good film typically does not encompass more fidelity to the source material (ie: a wisecracking Spider-Man) like it does for fans . If the critics believe that the film fell short or was just another passable/okay Spider-Man film, then to them it may very well have felt "unnecessary".
And I don't think that slapping a popular director's name onto a film actually helps with reviews. If anything, it bolsters expectations of what the film will be like and leads to more disappointment/scrutiny if he/she delivers anything less than their previous body of work.