I originally put a huge wall of text, but I'm going to keep this simple:
The loot curve is awesome throughout much of the game, from the forest to the snow biome. The difficulty of the next biome is worth the loot haul you get, in general, and is exciting to overcome in order to get sweet loot.
When you hit the wasteland, however, it falls flat. No major jump in quality of items found, I was already finding the best guns in the snow biome, and the end loot chests don't have more slots and are just as rewarding as in the snow biome. Im sitting at about 1000 loot stage in the wasteland. I found 16K weapons at most in the snow biome, 32K armor here and there; Same thing in the wasteland in a tier 5 POI.
The short of it is that if we're going to go up against 12 rads charging us in the streets (and another 1 or 2 every 10 seconds) in the wasteland city, then go through an entire tier 5 POI dumping about 1000 bullets to do so and live, the pay off needs to be in line with that.
Keep up the good work!
Bonus feedback: the end loot of POIs is too poor, in my opinion, especially when it comes to tier 4 and 5. The quick fix is that tier 4/5 have proportionally more slots in their end loot chests.