Hey Robert - you might get a reply from someone at Atlassian here - but I can provide you with a link relating to these changes, which contains a little about why (but it's not a lot of info on the reasoning).
"Once everyone is on the new issue view, we'll be able to ship improvements and fix bugs faster"
So, this is a change needed for Atlassian to be able to move forward with future developments, but this is just the tip of the iceberg.
Here is a bit more related info:
new issue view in Jira (jira ticket)
New Feature Policy
For JSM June Challenge #2, share how your non-technical teams like HR, legal, marketing, finance, and beyond started using Jira Service Management! Tell us: Did they ask to start using it or...
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