Data Types basically take the place of various data validation options in Excel and Google Sheets. But, could you take the data type a step further by adding optional Min/Max ranges? For example, for a Percentage, you may want to limit it to 0% to 100% (for progress). For numbers, you may want to enforce integers, or a particular range. Editing the data type seems like the logical place to do this.
Great ideas here. We have plans to extend the capabilities of our data types and this makes a lot of sense as part of that effort.