Of course spinning up a hello world of anything is easy. Now introduce monitoring, change controls, version upgrades, multiple environments and regions
It's not that it's necessarily complex. But if you don't need it, don't use it. The business could use your time elsewhere
For a redis cache? I think you're way over-valuing the effort it takes to keep a redis instance running.
For a persistent store.. sure... but that's true for PostgreSQL as well, which has some pretty painful major version migrations by comparison to other options.
It's not that it's necessarily complex. But if you don't need it, don't use it. The business could use your time elsewhere