When your opponents are lying, cheating, and breaking their own made up rules (no supreme court nominees during the lame duck session unless nominated by a Republican) your characterization is uncalled for.
Yes, the right have been doing it for a long time and it works. Either make it stop working, or copy the thing that works. Don't just handicap yourself to a guaranteed loss.
The rules are that the executive can appoint judges. Right wing executives take advantage of this rule. Doing the same from the other corner seems reasonable too. The failure to do so means that the Democratic party is incompetent, uninterested in enacting their own alleged policies, or some combination of the two.
Some people say "if you're not cheating, you're not trying" but this is even a level removed. This is a perfectly legal move that they've denied themselves for no material reason.
