This doesn't seem to be targeted at the frequently-swapped use cases that SD cards are made for. It's more about adding repairability/upgradability to internal primary storage in small devices. For that use case, the 4x throughput advantage is probably reason enough to rule out SD Express.
I don't think the connector is the problem but the devices you connect to. RPis are notorious for having a poor lifespan due to reading/writing from the SD cards, but I think that's mostly due to the cost tier of a $30 computer.
I'm running a batch of SBCs which boot from SD cards as home or forgettable servers. None of them died due to SD card failure yet. A good SD card with a little optimization keeps the flash media wear out at bay.
What little optimizations?
Like writing logs to RAM and syncing back to disk daily or only on reboots/shutdowns, keeping high-write applications on a USB drive and providing the biggest cache possible by slimming down the OS memory footprint.
This two things reduce the hits to SD card substantially.
> RPis are notorious for having a poor lifespan due to reading/writing from the SD cards
How does the Raspberry Pi deteriorate from the interaction with the SD card?
It has more to do with the garbage $2 power supply someone had "lying around".