The Splurge more or less contains all the upgrades that don't fit into any of the five previous buckets.
To that end, they are frequently deemed as 'nice to haves,' as opposed to crucial upgrades.
However, it is easily argued that Account Abstraction is a necessary user experience upgrade, without which it would be near impossible to reach mass user adoption.
Similarly, EOF has the potential to fix many of the developer experience issues that plague builders.
EIP-1559 rectified a monetary policy error, wherein all network participants were severely overpaying for miner / validator security.
It too provided a massive user experience upgrade by streamlining gas estimations.
Various privacy focused roadmap items are also bunched in here, further strengthening the argument that The Splurge is The UX Tract.