As well as WWI levels of moral pointlessness.

I'm sure Russia could move forward in some places, but they don't need to. At this point all they need to do is win the war of attrition and keep their defensive positions (which is obviously much easier than attacking). Ukraine will come to them anyway.

For Russia's sake, I hope not. By year 4 of that war people were dying by the tens of thousands on individual ill-conceived military maneuvers. And unless Poland or Hungary enters the war on the side of Ole Vlad, there's no Western Front to take the pressure off.