Virgin Orbit offers expensive, inconvenient, unreliable launches.
For instance, Electron costs *half* of what a LauncherOne will cost you, and RocketLab is more reliable, has more launches under their belt, and offers a fantastic truly customer-oriented system.
The supposed advantages of air-launch aren't such. First of all, it's for the most part a lie. "It's just a plane, so we can launch anywhere". Well, except you do need pretty much all facilities except for a launch tower at your airport. And you need authorizations from everyone, from the FAA to the airport itself, local authorities, etc. Launching from another country? Even more bureaucracy. And it'll only be ok if it's a NATO country and the US gives the Ok for it (because ITAR). So all of those advantages evaporate fairly quickly.
If you want cheaper, and your orbit allows it, you can get on a SpaceX ridesharing mission. Anywhere from 300k to around 2 to 3 million for the max payload capacity that LauncherOne can handle. And you're launching on the most reliable rocket in history.
The problem with their last launch is a fundamental flaw, not necessarily on design, but on how they do things. Their processes are horrible. Sure, they aren't the same company as Virgin Galactic now, but they used to be, and they obviously inherited the same culture.
VO was already not very appealing, but now there are even more options, and more are coming. VO hasn't gone the way of Astra yet for the same reason BO isn't out of business: A big ego with big pockets behind it.