anyone who can actually generate electricity from his body as opposed to wearing vibrating-shocking-gloves on his hands has greater potential to do much more damage
It's like comparing Iceman to Mr. Freeze.
Too bad Electro & Shocker are joke villains since they aren't exactly diabolical geniuses (cept Electro in the 90s Animated Series).
They always mess up the costumes, if they do Electro they aren't going to do the starfish mask.
Electro might be in 3 anyway Grace would be good for either him or Mysterio.
Also, Shocker's a two-dimensional character while Electro has his self-esteem issues and the suicide attempts. He'd be great as a side villain to Mysterio, Venom, Kingpin, etc. in future movies.