Wouldn't the de-extincted species probably face the same pressures that made them extinct in the first place?

I guess if you dumped them in the wild and wished them luck. But they would probably actively manage the species.

Right, so we'd be keeping them in zoos, so not really helping the biodiversity of nature.

A managed population is wild. You can do a lot without having to keep an animal captive in a zoo.

I see. I guess that it could also help biodiversity efforts from a PR standpoint to have wildlife reserves for a 'charismatic' animal like the dodo, similar to how everybody wants to protect the panda bear.

Could do. There's zoo pandas. There's the reintroduction of wolves to Yellowstone where they're less likely to get shot by farmers protecting livestock. Anti-poaching guards for wild rhinos. Seagrass restoration for manatees. Programs for people to grow baby mussels in fish tanks so they can be relocated to the ocean. Hunting programs for deer culling. Giving out free native plants and seeds to help native birds. Lots of options depending on the needs of each species.