Or maybe Elon just overhypes how amazing everything is?
Remember how enhanced summon went from MIND BLOWING to "it almost doesn't suck"? as they were almost a full year late delivering it?
Or, to be more fair-maybe he has a deeper understanding of the engineering and the impact it'll have to future Tesla efforts- so it's mind blowing to HIM but not so much to the famous Mr. Market we all talk about who doesn't know WTF an anode is he just knows "amazing batteries in our $140,000 car, off this tiny prototype line.... and coming later in stuff not yet on the road and built in the factories that aren't done yet in germany and texas" isn't TODAY EXCITING stock news.
I think battery day will give analyst some color in the infamous 50% yoy growth Elon guided for. Autonomous day couldn't really do this. In house battery production is another way to reduce cost, especially with a manufacturing break throughs. Elon will probably share information not only on batteries but all the manufacturing breakthroughs they have been working on including how gigafactories are being built in record time, the cost difference between the factors, expected car output after giga press and a reduction by a factor of 10 in complexity..etc etc. Recent execution at least give this part of Tesla a lot of credibility vs autonomy.