If you organize the inside using MOLLE-capable bags, then you can quickly and easily expand your storage by just attaching those bags to the outside.
But it's "tacticool", so it's not for everybody. My Dell XPS 13 and a whole lot of other things fit into it easily. Plus there is a hard plate on the back that protects the computer from impact from that side of the bag and gives it support (it's removable).
Plus, I seem to be accumulating a number of MOLLE things from trauma kit to Leatherman to pepper spray.
Currently, my laptop messenger bag is from another defunct company, Hlaska, which is currently overloaded with a MBP 13 and minimal power/EDC stuff.
I should probably upgrade to a MOLLE bag so I can carry my backup HDD without using a reusable shopping bag AND messenger bag.
1: https://countycomm.com/collections/bags/products/mid-range-b...
They are very convenient tons of storage space, everything is easily accessible, best back support I've seen outside of really high end trekking packs and they are durable as fuck.
I've had some expensive backpacks from the likes of samsonite, they look good but they tend to age very poorly (I might be abusing them too much) and they aren't nearly as comfortable to use at the 5.11 ones.