I don't feel like putting weights back on the rack, so I'm not going to do it.
Does the person who brought the weights in the gym want you to re-rack them?
Yes, but they have employees for that, people who don't have anything better to do
You should be respectful of other customers and of employees when you work out in a gym. Employees shouldn't have to run around re-racking weights after every person, because they have lots of other tasks to attend to.
What? I care and always offer to help (even when no one ask me to) and I'm to busy to deal with this, I got better things to do.
You should build in the time to put them back. It is expected to follow the social conventions put in place at a public gym.