The fact that /var can do some math does not mean it can do everything that $calc() does. Just using
//var %a = 1 + 2 + 3 will fail as well. That is simply a limitation of /var and isn't a bug. I'm not sure that there is any good reason to extend /var's mathematical abilities when it's just as easy to include $calc(). If you think it should be extended, then that's a feature request rather than a bug report.
