And i do agree with caging sizes to an extent. From a business/breeder standpoint, it would just take up way too much room to give each snake a huge cage. The animals are not being 'abused' in any way as long as their requirements are being met with temps/humidity/food/cleaning etc. So while the animal might not express its full behavior, it is still being taken care of and flourishing.
Now from an owners standpoint which i am as i dont intend to breed, i like to give my snakes the most room i can afford while still keeping it reasonable. I mean i just dropped $2000 down on 3 AP T25s for my SD retic and big boas and they are loving it but would i like to give them a 20' cage, sure but thats just not feasible even though i have my own home. It's basically a juggling act between seize of the cage and size of the space available.
I personally try and offer my snakes a cage length that is at least 3/4 their body length. This is why i went with 6' cages instead of something like 5' cages. And depending how much more my retic grows, I might end up having to bite the bullet and order him an 8x3 AP T65 and then find a place i can put it.
So personally i see both methods working. I mean smaller caging or racks have worked for years and years and years and all the CBB snakes being sold throughout the years are proof of it. But also the large spacious natural setup works well too. For me, i go more minimalist set up for ease of cleaning but i do interact with my animals a lot and take them out of their cages for outside time as well as indoor enrichment.
Anyways I'm rambling but bottom line is i see both methods have merits and both working depending on your set ups. It's the same as the old argument about RHPs vs Flexwatt. Both work equally well depending on your set ups.