I am not sure how you think line breeding works but selective breeding is how quality animals are produced in the first place. Differance in color and patten may not mean that much to you but when breed for there traits they inhance furtue offspring for the same trait thus making them more valuable to the individual trying to line breed for a trait. Now when you say a normal jungle Jag for $700 what do you mean normal jungle jag they are a morp not some natural sub-species varient of the carpet pythons. You can't make a price comparison and say a Jag is over price or not worth it when you compare it to a tiger or a striped coastal. All three are totally diffrent and it is like comparing apples and oranges. look I am not trying to poop in your wheaties I just don't think you fully understand what you are talking about.
Any snake in to big of an enclosure will get strressed out and may go off feeding, so yes.