As a tenant you are freed from the property maintenance; instead you are at mercy of landlords for that aspect, but I think they should and actually do the maintenance in practice.

Many properties in SK are offered via a peculiar scheme, the Housing Subscription System 주택청약제도, which is a result of convoluted history. Basically you should have a dedicated saving account, and your eligibility will be scored by multiple factors including the deposit sum of that account and in particular the period of non-ownership. When you buy a house your non-ownership counter resets; Jeonse will keep it. So if you use Jeonse as long as possible, your chance of being eligible for this scheme will increase.

They don’t want to is the idea. They want to live their for two years and then get their money back so they can move somewhere else without risk of things breaking or housing market going down.

The owner might not want to sell, or they might only want to rent. Also, the deposit is fully refunded at the end of the term in this type of rental. In a jeonse, the deposit is generally 50% to 80% of the value.