I am a big fan of Venom and while the first Venom movie had many major flaws, I ultimately enjoyed the experience as a fun guilty pleasure. It was a very different take on the character and I am interested to see what is reserved for this iteration going forward.
However, I can understand why people feel dissociated with these films. First off, while it is a different take on the character, comic book fans don't like it when movies change the source material. Especially if that change is the total removal of one Venom's major roots: Spider-Man. While Venom has had some stories without Spider-Man, his history will always be traced back to the wall-crawler and removing that piece of history kind of removes a piece of Venom's identity. This causes no Spider Emblem, no webs, no disgruntled history as a villain, and no universe with Spider-Man. There were high expectations placed, but they weren't met. It becomes more frustrating when both Venom and Spider-Man are having films released simultaneously, but they're both different universes. They shouldn't be separate but they are.
Then there's the general consensus of the first Venom film. While many agree that it is a fun movie (myself included), the general consensus is that it's a bad film or one of those "it's-so-bad-it's-good" films . The movie drags up until it gets to Venom, the villain sucks, the tone is not fully fleshed out, you can't tell who is who in the final battle because they're both dark colored symbiotes fighting in the dark, and overall the story is meh. And this all boils down to the fact that they tried making a Venom origin film without Spider-Man. It didn't stick the landing as an origin film because of this.
Both of these factors are what have people hesitant about Venom 2. The first movie wasn't so good for them, so they're not really expecting much out of the second movie. Carnage doesn't have his iconic look, so expectations have been broken. And lastly, still no sigh of Spider-Man. Many believe that if the Venom movies become more successful, that rift between Venom and Spidey would grow even further.
Needless to say, I am optimistic about the next Venom film, but I understand everyone's frustrations with it.