The Senate is about compromise. The filibuster encourages bipartisanship and sets the Senate apart from the House. It ensures protection of the minority so that change isn't too radical, promoting stability in government. There are many things Democrats can do without removing the filibuster, such as reconciliation and judicial confirmations. If the filibuster is removed, Democrats are at the mercy of Republicans when the balance of power changes hands. Since it is likely Democrats will constitute the minority of the Senate for much of the future, it would be unwise for them to erode their power.
First, the Senate should be destroyed.
Second, the Senate is already unfairly biased towards Republicans, giving the minority of Americans in less-populated GOP states much more power than the majority.
Third, the Senate is no longer about bipartisan compromise, if it ever was.
Fourth, sometimes being radical is both good and necessary.
Fifth, I'm fine with Republicans also having no filibuster. Last time they had total control they only cared about tax cuts and justices, their true priority. Let people experience what Republicans want to do, or call their bluff on it.