If you have a bunch of plugins and you have them dongle-authorized then a system failure where you then later reinstall everything (assuming you couldn’t rebuild from a clone/image) - or if you need to upgrade and can’t easily move software ‘across’ with authorizations - then it’s way easier with a dongle. Just install the management software for the iLok / eLicenser and you’re good. With software/serial number authorized stuff you often have to go through a million steps to get it re-authorized.
Likewise, if I go out and work in a studio (post-production) I’ll bring my iLok with me with Exponential Audio’s Phoenixverb Surround as well as iZotope RX. So I’m never without those two and all it takes is an install and then plugging in the dongle.
I find it to be easy and convenient and less to think about than moving authorizations around via software or a web interface.