"a motor that runs forever if properly maintained"...
That perfectly explains why these are in demand.
It's a shame that modern engineering does not seem to offer any improvements in longevity. We may have much better fuel economy available in modern trucks, but reliability has been consistently lacking for most recent generations from nearly all manufacturers including Toyota.
I personally think this generation of Toyota is the sweet spot in the current progression of vehicle technology. They are 'modern enough', comfortable, extremely reliable, and I find the styling and sizing to be appealing (this is true for these Tundras, 1st gen tacoma, and the 3rd gen 4runner all of this era, late 90's to early/mid 00's). They have early OBDII systems for easy diagnosis but mechanically still easy enough for the common guy like me to repair myself. Computerized, but just barely.
And still at a fraction of the price of a new (large, ugly) Tundra, which it will likely still outlive, despite being 20 years old.
Shoot I think I want to buy this now...