Well one benefit is usually potted plants will have roots on them. Some bare roots will also, it just depends on what you get and whether it's pulled directly from stock or cut, and of course who you get them from. A lot of places don't actually grow their plants and they just kinda hold them in limbo till someone buys them, so it's hard to say.
I can tell you that I base my decision to trim bunches on how the plants look, along with how big they are. I have some hygro plants that are a few feet tall, so with those I just trim the tops and replant them. This serves a few purposes, but the main idea (for us) is to prune the stems to encourage more compact growth.
Because of that, when I send some in an order they may or may not have roots on them yet. Some plant stems will lay over slightly when they are planted into emersed culture and result in slightly bent stems towards the bottom, so they are usually trimmed prior to shipping as well.
Whenever bare root bunch plants come in from the farm, they are almost always rootless cuttings.
Potted plants typically do not have any more stems than a bare root bunch, they just tend to have more extensive root systems since they've had time to establish themselves in a pot (usually).
On a side note, roots aren't a huge deal, most plants put them out within a week or so on their own if they are doing well in your setup.