OpenBSD has an older fvwm installed in base. Licensing reasons. A newer fvwm2 is part of ports. So that's two different versions already available. Adding fvwm-3.X.X would really cause conflicts. I would much rather see fvwm2 and fvwm3. That avoids some tricky work making them both installable. As fvwm3 will diverge, I can easily see someone wanting a stable fvwm to use or go with a changing fvwm3. Multiple users are very likely to want two different versions. If you like your current setup, why require battling with configs? If you want changes, no problem with config changes. Everybody happy.
There are already three flavors of fvwm available in ports right now, plus 1 installed with base system. Sure, the conflicts can be handled, but IMHO offering fvwm3 versus fvwm2 is easier for end users new to fvwm. Thanks for the hard work! Chris Bennett