40 Li-Po cells? :p

But seriously, their choice to make the battery pack out of many smaller cells rather than one monolithic block is good for the consumer. The smaller cells are widely available, so the battery packs could, in theory at least, be rebuilt when the cells reach the end of their service life.
The cells are likely welded together, so you couldn't just go out to the drug store and buy 120 C batteries and pop them in, but the proper equipment is publicly available if someone chose to go into business rebuilding these things.

And Panasonic the OEM mfgr does sell the cells catch is you have to buy hem in 10k lots