It simplifies their manufacturing, also allows easy upgrades that many want at a future date.Shit, you aren't kidding. I stand corrected:
https://teslamotorsclub.com/tmc/threads/software-locked-batteries.146097/
"Hey guise, we're a "green company" looking to save the world and reduce harmful greenhouse gases, but if you want more range with the already equipped battery charge, you'll just have to burn more electricity off the grid, carry the extra weight, and have us manufacture that extra waste. Or you could just pay us more money."
Actually I found out my cheap Toyota is somewhat the same too. they were all wired for upgrades so if you want upgrades at a future date, the dealer can easily do it. Tesla just carries that concept to the extreme.