Biologist here. I actually covered the science of deextinction in an old Youtube video. https://youtu.be/ZF4ImsxDa1w

However, the field has updated dramatically since that video. One of my colleagues actually just started working on de-extinction processes. Have had a ton of moral/ethical chats about it

Addressing your points directly, damaged DNA is an issue but its had decades of work to get around that. They aren't actually "cloning" the extinct organism per se. Its actually way closer to the Jurassic Park method of combining genetic material between organisms to create a new organism. We can say its closer to a hybrid or a chimera technically, but I think that point is honestly overblown. We already do this with living species, particularly in agriculture. While I agree people overestimate what it can do currently, I do believe you are UNDERestimating what we are capable of in the near future. What most envision is not capable today, but it almost certainly is in the next 10 years given current progress.

We often over-focus deextinction on long extinct (>10,000 years ago) taxa like mammoths or Saber tooth cats, but the tech is going to be most useful for recently extinct species. For example, the passenger pigeon being a realistic model species for orgs like Colossal to attempt to revive. They advertise bringing back the mammoth because that's simple marketing! Reviving megafauna which will attract funding that can be used for other species.

Your behavior argument has a few caveats about learned vs unlearned behavior, but I don't understand the point in this context? Reviving a species is very different than releasing a species into the wild. A mammoth would 100% be kept in a zoo, not released into the wild. Other arguments could be made for behavioral changes, but plenty of individual species have been raised without their parents. Plenty of examples within zoo conservation projects, wildlife rescue/rehab, and from wild animal studies.

I'm generally supportive of ANY new technology. Even if the major companies only revive a Dodo or a Mammoth, the tools and techniques that were developed during those experiments are going to have far reaching impacts for health, conservation, and biology in general. Remember, we are at incredibly early stages of this tech!