You make the same mistake as many others, believing that if Steve was still there, everything would be exactly like it was the day he left. Steve would have evolved along with the company. I see zero evidence that Steve would have kept upgradability, in fact having the customer open up his computer seems very un-Steve to me. Apple had plenty of proprietary and closed technology developed under Steve Jobs.
And your price comparison is misleading. Upgrading your 2015 Macbook to 4TB still makes it a 2015 Macbook. A new baseline 16” with 4TB will be a much faster computer, at 3600$. Just because you can spec out one at 5000 doesn’t make it a fair comparison to upgrading your old one. That’s still a noticeable difference from 600, but a misrepresentation nonetheless.
I also happen to disagree that the products are less exciting. You’re just being nostalgic, and compressing memory. People still seem to think the Apple Watch for instance is boring. For me, it was life changing.