From @epriestley's suggestion on T11481#193202, I'm elaborating on the use cases for workboards to have a default or subset of create task options.
There are a few use cases where users are creating tasks while primarily interfacing with a project's workboard. The current methods for creating a task from a workboard appear to use the default create task form.
A user creates a project with restricted membership. They use the workboard as a means of managing tasks fairly regularly, and the task status/column changes frequently. In this scenario the tasks are not being used as units of software development but something much more lightweight and not as long-lived. From within the workboard creating a task does not inherit the same restrictions as the workboard though the user was expecting/hoping it would. I suggested creating a created/edit form via #editengine which would default the policy to the project. The default edit form behaves as he would expect, however it is not available from within the project workboard.
In a different scenario, I am working with an outside company to manage cooperative work using project workboards. We use several workboards, one to represent each version we're planning. For them, I've made a specific create form which default adds me as subscriber, as well as sets permissions so both the internal team and external team can see it. For them it's the only create task they have access to which is convenient, but as we begin to plan out more versions being able to have a default project set when created from a workboard would make things a bit smoother. It's fairly frequent that they create a task which doesn't get assigned to any workboard when they meant to put it on a version, so I generally have to review every one to make sure it's in the appropriate workboard. I have also occasionally created tasks but not assigned the right space/policies for them to see it, and wonder why they don't respond to my comments~.
An issue I would foresee is the global create menu conflicting with workboard create options. Some users are using the Create Task available from the global create menu and others are using it from the column in the workboard.