Sandboxing does not come for a free, as it creates more complex development APIs and a performance hits.
Would still be nice to have the option to opt into, for example, running as a WASM isolate - given the option of a robust sandbox, some plugins will find it desirable to migrate and gain the secure badge or however isolated plugins are marked for user identification.
But There are plugins where it’s going to be too much of an uphill battle to move to that model though. I still think on balance having sandboxed plugins, however they’re implemented, would be pretty nice.