What, you don't know anything about the engine developer? Why should engine developers optimize their software for new hardware? To make idiots buy a new computer?
You can't mean newer operating systems by "newer systems". Because some important Linux distributors offer 32 bit Linux systems, for example Salix (Slackware), Mageia (Mandriva), Puppy Linux. I just loaded MX-Linux 23 in the 32 bit version. It's only been available for a few hours.