It doesn't have to be that way, small improvements to the website would allow those changes. Several years ago I was booking direct on RCL's website and I could change cbins or categories without any help. Upgrading internet or beverage packages online should not be an insurmountable problem. Maybe things like shareholder credit, which doesn't affect a lot of people, may require a request to be submitted. These are not insurmountable problems especially when your company has significant financial problems.
There need to be some significant changes that do not negatively affect the customer experience and TA commissions are a huge expense that must be reduced.
An alternate approach might be to drastically slash commissions that would eliminate kickbacks to the customer. Perhaps this means that only Big Box TAs will survive. Perhaps it drives a pay per service TA industry.
I don't know the solution but I do know that the commission expenses must be reduced.