I used to be worried about the soldered on SSD, since that will ultimately be a point of failure... but I did some calculations, and with my usage the SSD would go bad in 30 years or thereabouts. Something else will go bad on the laptop before the SSD fails, especially the battery.
Personally I've never had a device with built in storage or RAM have parts fail on me... the iphones and ipads and now Macs have worked great for many years.
I had a couple white polycarbonate MacBooks, which I easily changed out the ram and harddrive, and both those parts went bad eventually. (a bit expected for the hard drive)
I think the soldered SSDs just solve some problems that are more important for Apple. It makes it easier to put some of the fastest SSDs, can make the devices smaller, fewer points of failure and simplifies manufacturing... and a very small amount of users will actually replace the storage. Also I think as devices get smaller, Apple just sees external storage as the natural solution to this problem.
My biggest problem is price, and being technically inclined enough to upgrade my own it was nice being able to avoid the apple tax with simple upgrades.
SSD prices on Macs are much better than they were though, they were stuck on 128GB for so long. 256GB is an okay starting point, and it's good you can go up 2TB if you really want to.
I upgraded my M1 Air to 1TB... but since the M1 Air is otherwise great for the cost, it was a little easier to justify.
For good or bad, the core hardware of a Mac is now more iPad like than ever. I've seen so many old iPads still kicking around, I'm okay with the Mac being more like an iPad.