easier way for data entry validation and dependent/filtered lists

Noticed this when trying to create an end user model and wanting to only allow valid data entry....

While there is a way to create dependent filters for lists in modules, in reality it is not intuitive and (in all likelihood) too time consuming for most users to attempt. Especially with several dimensions this adds a lot of complexity to possible solutions. In a similar vein, there is limited way to enforce what a user can enter in most fields (eg, all numbers must be greater than or equal to zero). As another example, in the same module it is possible to pick an end date before a start date without forcing validation (ie, end date greater than the start date) -- this should not be possible. 
While we can create rules to re-enforce preferred data entry rules, however they are typically hidden from view, outside of the line item and do not force the user to enter a valid amount/selection/date/etc. In sum, we cannot enforce good, valid data entry yet.  That's the request...help with data entry validation.

In light of the newer page selector filters & show/hide in NUX, this seems like it could be an easy win for managing what users can & cannot enter into module fields by adding some of these capabilities to our module line items.

Thanks for your consideration.