We can all have our opinions about what Russia should do, but bear in mind you learn more from looking at what is happening and thinking about what could happen than by deciding what ought to happen when you have no way to influence the outcome.
You may think that Russia should be more aggressive but you don’t have available to you the full picture that Russia sees. There is more to this conflict than just the military side, there is a larger diplomatic, geopolitical and economic game being played.
In the end their decision may surprise you, just as it is meant to surprise their enemies, to keep them guessing and unbalanced.