Sure, but you could selectively breed rabbits for 1,000,000 years and get a glow in the dark rabbit; GFP is just a protein like any other - if you painstakingly selectively breed for a specific DNA sequence, you'll eventually get it regardless of your starting genetic pool. Classic selective breeding is a form of genetic modification - modern genetic modification methods are just way faster.
I agree that we don't currently know enough about genetics to utilize genetic modification without unforeseen side effects, and so there should be limitations on what we're able to genetically modify until we can show that we understand it well enough to meaningfully minimize potential issues, but those same issues occur with selective breeding - they're, again, just slower.
That's the way it's been for a while now. There's so many crises that we just run to the new one every few days, forgetting about the old one and never actually resolving any of them. Considering how complaisant the burnout makes us, I'd imagine it's not entirely happenstance that things are so hectic.