I've never thought of this before but you are right, there isn't currently a way to display actual internal rates unless you do it via WI or Crystal reports. The field value is basically used to calculate revenue and total cost so the internal rate is always behind the scenes (well, it is visible in the Admin zone appropriately).
It would make sense that the rate should be optionally made visible but more customers find that they want to be sure no one see's the internal rate so it hasn't made too much of a priority in terms of developing in the functionality to make it visible (and associated permissions).
It is possible to get the hourly rate for anyone logging time against a task. It is pretty basic: create a Task custom calculation field and take the Actual Cost / Actual Work (Hrs). This field displays in the Task details screen and Task Tab view's only. It will only work for a single assignee task, or multiple assignees of the same rate.