Here's my take -- I didn't get a BLTouch for many months, as I set up my bed with 3 screws (even 4 makes no sense at all, IMO!) and manual leveling just isn't that hard then. BUT--
Then I wanted to try PEI sheets... well, new complications. PEI has a reputation for liking PETG filaments a little TOO much, and PEI prints might not come off at all if you have the squish a little too much. So, I got several glass sheets and put PEI on one of them. That makes the sheet thicker, so switching between PLA and PETG now meant a bed readjustment every swap. Not necessarily a re-level (I have one Z motor), but a Z stop adjustment at least.
Then there is the OCD factor -- wondering whether the bed if still flat, even if you didn't change the glass. Because it still needs to be readjusted from time to time and that "time" isn't fully predictable.
So, enter the BLTouch. Change the glass or don't change the glass. Bed slope changed a little or it didn't. Neither matters anymore. Just click the print button and go.
That makes it worth it for me. Necessary, no. But fewer screwed up prints from something going wrong (was it the bed leveling? Maybe....?) can really be a good thing.
[Edit: If you do want to have easily swappable glass for different height reasons or to have one prepped and ready to go as a print ends, so you can work through cool-down times, a great way to do it is with silicone sheet.
It's made for heatsink gasket in electroncs. Put it between the bed and the glass. Then just lift the glass and put the new one on, no clips to mess with or to worry about the nozzle or other stuff running into. The sheet will keep the glass from moving laterally, not even a little bit, very high friction]