Older versions are not supported anymore (you would have to go back more than half a decade, which is an eternity in security terms) and do contain known/ unfixed security issues (WAN side, LAN side and wireless side), which preclude them from being used in any capacity.
Just to provide some background.
It is currently proposed to drop support for devices with 'only' 64 MB RAM right now
and 8 MB flash are hard at their limit as well.
(and yes, I am serious about the recycling centre suggestion, I already had to do that with with four of my own devices, with two others (8/32 and 8/64) pending this path, when I next lay my hands on them (they're already powered off/ unplugged for a long time).