My incentives to run a non-pruned node are these:

1. I want the option to be able to check the status of coins in different wallets. For instance. I need the whole chain so I can scan for coins related to that wallet.
2. I want to be able to leave my node off for a while (a month or two even). Depending on how aggressively you prune, this can be an issue.
3. Running a lightning node on a non-pruned node is easier.