Maybe its me, and I might need this explained because I just dont know.
There was the Spiderman Movies with Toby McGuire. These were released within the last 10 years right?
Now there is "The Amazing Spiderman" with the same hero, just seems he got his powers differently. Same essential pretense in which a guy with spiderlike abilities fighting crime. I don't see the difference or the need to make another one.
Kind of like the difference between the Hulk, then the next year releasing the Incredible Hulk. Same movie, different actors.
Short story, diference in creativity between director and studio made studio dump director and crew and restart a new,problably since they obligatin with them lied on spider-man movie,this new one is AMAZING spider-man,so no liability.
the original movie was looooosely based on the mainstream spider-man story, this one this more focused on the ultimate universe spider-man while loosely geting elements from other medias as well.
and for the need, money, always money. Also on hulk, the first one was from universal studio, the newest was from marvel comics own studio,so they rebooted him to fit into their new plan for integrated cinematic universe.