Actually, her association to the St Bartholomew is the proof she was a very weak leader.
That slaughter was orchestrated by her third son, Henri III, without her or his brother the king's consent.
It went totally against all her policies so far.
But since her favorite child decided to make a show of power, which kinda backfired, she initally condemned the slaughters, then realised it was family who did it, so coverd for family.
That's the proof that even before Henri III's reign, he was the man who had a real influence in the realm, and that his mother just did what she could to follow.
So, her association with the slaughter is meaningful, but not in the sense she should be accountable for the deaths. Modern historians no longer blame her for that.
It is meaningful in that she was a weak leader, whose policies were inconsistent, who only managed to maintain her sons in power in order to have all of them die wihtout a heir.