GPLv2 says: "You may not impose any further restrictions on the recipients' exercise of the rights granted herein.".
GPLv3 explicit says: "not allow patents to restrict development and use of software"
GPLv3 also say that you can not use hardware restrictions as a trick to circumventing the no-further-restrictions legal requirement.
One could argue that GPLv2 already include everything GPLv3 do in form of that single line. Doing such interpretation would for all practical purposes upgrade every gplv2-only project to the same conditions as of GPLv3 (but with fewer license compatibilities). The FSF clearly decided not to go that route, and created the GPLv3.
GPLv3 explicit says: "not allow patents to restrict development and use of software"
GPLv3 also say that you can not use hardware restrictions as a trick to circumventing the no-further-restrictions legal requirement.
One could argue that GPLv2 already include everything GPLv3 do in form of that single line. Doing such interpretation would for all practical purposes upgrade every gplv2-only project to the same conditions as of GPLv3 (but with fewer license compatibilities). The FSF clearly decided not to go that route, and created the GPLv3.