Because embedding new species into an untested environment can be devastating. My example is the accidental import of tree snakes to Guam, which resulted in the complete extinction of all birds on the island, because the snakes ate the eggs faster than the birds could adapt. There are numerous numerous other examples of accidental release of animals destroying ecosystems.

I think there should be a ban on "owning" custom sequences of DNA, as it will eventually lead to an accumulation of most of our "biological capital" in the hands of very few companies, which could then effectively control what and how we eat (and many other things as well). Already now most biodiversity has vanished from agriculture, with only a handful of different crop species accounting for more than 99 % of all harvests. This is highly dangerous economically, politically and environmentally.

The biggest problem is they're not open source. What went into making that organism? Is there a standard for documenting this and reasonable public disclosure when relevant?

Foods have ingredient lists for a reason.