Jackal definitely should've been in the show in my opinion. If they had time after his death, they could've included Carrion as well.
I also think they should've replaced Hydro-Man with Sandman. Hydro-Man's lame in my opinion. Sandman is sooooo much cooler. They would've just needed to find a different way to kill him (sand doesn't evaporate; a quick science lesson). Lol. Or maybe put both in some way and included the Mud Monster from ASM # 217 (or something like that).
Oh yeah, and just as a pointer-outer; Rose WAS in the show. Buy the Venom Saga. See those guys who Kingpin was going to sell the Promethium-X to? Look carefully at the one who says: "It's useless!" Recognize him? The Rose. But I do wish he had a bigger part. And that one clearly wasn't Richard Fisk.
I probably also would've enjoyed Cardiac! He is awesome! And how would this show portray him? 100 times cooler, I bet!
Another few nice additions would've been the Beetle, Molten Man ("Wedding" sequel episode?), Tarantula, Will O' the Wisp, Hammerhead Ghost, Man-Wolf, the Frightful Four, the Sinister Syndicate, Spider-Lizard, the Terrible Tinkerer, Gaunt/Dr. Stromm, and some more made up villains like Mordo and Dormammu - they were awesome!