Looks great! Noticed a few things mentioned below...
1) Adding a text box does let us set max & min character allowances, but doesn't let us apply a charge if text is entered. Not sure what the purpose of validation rules is unless we can decide if that includes a charge or not.
2) When we add a validation for rule for a textbox control, we can no longer generate attribute combinations. Can we simply take any textbox controls out of the equation when calculating attribute combinations because they're custom options aside from inventory anyway.
3) Just as we have for "Specification Attributes" where we can add options and save them as templates, can this functionality be carried over to Product Attributes as well? It would save those of us with ever-changing color pallets and style availability (textile, apparel, etc) from having to change hundreds, if not thousands of products, when we could have just made one simple "color name" change or removed a particular option if it's not available anymore.
Thanks for your consideration on these points and thank you for your hard work! :)