It still appears more significant by the way futures trading works and the way it all bulked up to the last trading day, since there was no buyers after a certain point - because (certain) buyers were incentivized to wait until the last minute to submit orders, to get the cheapest price.
In a "real" market with physical oil wells + storage, wouldn't that decline in consumption -> storage normally happen far more gradually over time? (A drop over a week is less exciting than a down spike within 24hrs) I know it's less efficient that way and all of that, but this seems to make it appear like this drop in the market happened all at once.
A lot of non-experts will see the news this way regardless - it's slightly less exciting in context but still historic.
Futures prices were indeed negative, specifically the soon-to-expire May contract. June and beyond stayed positive, but this is the first time in history that the contract (any expiry) has traded at negative prices. This is a noteworthy event.