It isn't really odd at all that it's legal to rip CDs but not DVDs and blu-ray.
What's illegal isn't the copying itself. What is illegal is cracking the encryption or other copyright protection that's built into blu-rays and DVDs. Most CDs don't contain this sort of copyright protection - the music industry flirted briefly with it in the early 2000s, but it was an absolute disaster and quickly abandoned.
While it is technically illegal to crack the copyright protection on your personal DVD or blu-ray, if you're doing so for personal use only (such as copying a DVD you own to a hard drive system for personal convenience) such use is almost certainly protected under fair use provisions.