IPv4 without NAT was fucked at the design stage. To be fair: Who knew?
I was asked by my employer a while back to investigate this new www thing that has hit the internet (in around 1994 or 5, it took a while to notice) and I said it was a bit crap and no better than WAIS and GOPHER. I was using telnet on a Windows 3.1 PC and telnetting madly via a VAX and a X.25 PAD and what I now know was close to magic!
No one had any idea how things would turn out back then.
I'm actually quite impressed how long IPv4 has managed to work and without NAT (which I do mildly despise, given 30 years messing with this stuff), it would be stuffed.
Thank you for your work.