Unless you have to go online, at least for a time, in order to get new updates or additions. The point of offline playability is so that we, the consumer base, can continue to use the produce we paid for even after such a time as the provider of that product is not longer in business. IOI may not have incentive now to make it playable offline, but if they are planning to stick around long term they are going to need to be able to please their customers with products they can always use even when they stop providing services for it and have moved on to other products, or they will face issues once the time comes to cease services for that product. Not to mention the constant disconnects are fucking irritating and some of us would like to continue playing our game even when the servers are down, like it used to be.
Everything that’s not the main campaign mission on the main maps is online only.