Hi Michael,
The forms in Numbers for iOS are indeed handy, especially with the smaller display area.
Numbers 3.0 on the Mac does not have forms. But with the bigger screen area, adding and editing data right in a table can be more efficient.
One notable exception, I think, is if you are entering longish text values. In Numbers 3 you can of course Format > Text > Wrap text in cell. But then you can end up with a very long table that can be awkward to scroll through.
In iOS you can easily tap back and forth between a table with non-wrapping text:

and the data entry form based on it, which automatically wraps the text:

In your menu you could go to Numbers > Provide Numbers Feedback if you think this feature would be useful on the Mac as well.
SG