-In the Ultimate comics Gwen is a bad girl, punk rock type.
-In the Ultimate comics Max Dillon is not a lowly Oscorp Employee.
-In the Ultimate comics Curt Connors doesn't work for Oscorp and his Lizard form has a giant fin on it's back
-In the Ultimate comics Captain Stacy gets blown up by a Spidey impersonator.
-In the Ultimate comics Gwen is killed by Carnage.
I could go on and on...
Yes, aspects of it certainly seem to be derived from the Ultimate series, but you said: this whole movie series is based off the ultimate comics thats why.
As far as the Electro costume- if they wanted to make it work, they could've. The myriad of faithful superhero adaptations out there have already proven that.