I don't see either of those as abhorrent/inhumane practices, and therefore if people are willing to take the chance of those happening in exchange for the lower fare, then I have no objection to it. Some people are willing to trade quality for price, and as long as that market exists, there will be products and services to meet the need.

Now if they did something like take the bathrooms out of the plane to add more seats, I think there would be unanimous agreement that such an action would be crossing the line.

The original issue was that Spirit will only re-book pax on their own flights. This makes perfect sense as a means to contain costs. If they had to buy tickets with other airlines, fares would go up to generate the revenue to pay for those added costs, and they wouldn't be the ultra-low-cost carrier that they are.