Because you're tied to an expensive fixed-size SSD that you can't upgrade and the system hogging disk space reduces the space left to store the colossal 4K videos that every phone shoots these days and the VM snapshots you need?

Also every iOS virtual image includes identical files so you end up with about 5 GB of identical sample photos and other garbage for each iPhone image. Why they can't put them in a single directory and symbolically link to them is beyond me.

I say this with a 2012 MacBook that I've put a 1TB SSD in and a 2016 MacBook Pro with a fixed non-upgradeable SSD. Constantly fighting for disk space.

It is good tradeoff, except when you start running out of space, MacOS does not seem to clear the caches when you start running out of space. I have 128GB MacBook Pro and removing the ~/Library/Caches was somewhat regular excercise (it occupies 5-10GB usually) I had to do when I had lots of stuff installed.

- they don't start or run faster

- to borrow another commenter's words, I'm tied to an expensive fixed-size SSD that I can't upgrade (fortunately, I don't have 4k videos; unfortunately, I have too many d----d VM snapshots and the like)

Unless there is some compression involved, using more disk means slower starting and running apps. Edit: even with compression, I'd argue that uncompressing is faster than reading disk.

Nothing at all until you work somewhere that only buys 128GB models and the drives are soldered to the main board.