That's not caring about security, it's just not wanting to get blocked by firewalls. I don't think you can seriously argue that pirate sites care about security when the biggest thing on a page is an adware-installing, fake "DOWNLOAD" button.
My point is that by using HTTPS, these sites have demonstrated a higher level of proficiency with security tools than many more popular mainstream sites. I agree the scammy fake download buttons are a problem though, but that's what ad-blockers are for...
The firewall cannot do deep packet inspection on encrypted connections, since it cannot decrypt the data: https://en.wikipedia.org/wiki/Deep_packet_inspection
For example a firewall would see that you entered Google.com but not what you searched