There's a large gap between Saturday Morning Cartoon "remake the multiverse" vague evil and assaulting/enslaving/eating the player characters.
... Actually, assaulting and enslaving happened all the time on SMCs- like, every week or two. Capture the party, send them to the bylaxian gem mines to help the enslaved gnomes dig up the ancient evil we're looking for.
Eubani asking for the villains to commit more compelling evil acts, and then you Remathilis jumping to the extreme of saying Eubani's asking for the villain to "eat the player characters" and saying they have "edge desires" is a pretty rude way of exaggerating and dismissing a criticism.
Now personally, for this adventure, yeah the scope is huge and the evil is less focused on the villain doing awful things- it's focused on stopping the villain, we already know he's doing bad things. The separate earlier adventure is sort of evil, the cultists are kidnapping people. WotC 5e adventures have had evil stuff in them previously, I wouldn't criticize them in general for that and not every adventure needs it... although Vecna's a pretty weak presence in this adventure.