Soft water system debate

[Leland Barrow]

My wife and I are having a debate about an issue at a rental property, so I was hoping to get some advice.

Problem: Soft water tank started leaking at the bypass valve. I called out a company to replace an o-ring at the bypass valve. The company called me to tell me that the tank has a crack and needs to be replaced. The crack mysteriously appeared during the o-ring replacement process.

My solution: To leave the system in bypass and forget that the system is even there.

Her solution: To replace the soft water system because it is 20 years old and that the current renters are "good renters".

I don't see any benefit to investing in repairing, upgrading, or replacing a soft water system. When these renters leave I would just remove the system. The current lease is up in 3 months. 

Thoughts?