Fortunately, parks are indeed starting to take these precautions as Dollywood apparently delayed opening this past Saturday in the wake of Fridays outbreak.
SDC on Friday and Dollywood on Saturday are not the same.
Leading up to Friday, the storm predictions from the NWS had SDC in the lowest threat area, not even in the Marginal zone. Branson wasn't in a Tornado Watch until 5:16 pm; it doesn't look like SDC was ever even in the Tornado Watch area. The Tornado Warning was issued at 7:05. There is zero imaginable argument that SDC should not have opened on Friday.
For Dollywood, there were active storms on radar that would be approaching the park near opening time. Also, the storms had a history of being severe by that point. Way different than being in a watch waiting to see if storms materialize or not.
Closing parks when there is a possibility of severe weather is not the answer.
Improved infrastructure and procedures are a good direction and I'm sure that SDC is reviewing what occurred and how they can improve upon their procedures.