I believe that most of the time they are "updating" it to make it better in the code part of it. Audits are a real thing, and when you create a token with a contract that doesn't pass the audit check, then it is going to be a problem. I have seen many people who did it because they found some problems with the contract.
It is simple really, if CertiK for example says that there is something wrong with it, you update it, do a new contract, and ask them to check it again, and if it is clear then you stay with that but if there is some more then you make another one and check it again. One project I worked with literally had 3 contracts because of an issue.
This is true and very real. I have met with quite a lot of people back in the day, and most of them went ahead and made their own projects later in life. When you have been in crypto for so many years like me, you meet with a lot of people who get rich, and when they get rich, they want to get richer and they build new projects.
I have seen all of them get audits, and at least half of them would have another token with a new contract after the audit to fix things, and maybe like 5-10% of them would get a third one to get even a better one. Sure,it is a bad situation for the project no doubt, but having a shitty contract and sticking with it would have been even worse.