See [BUG-5618] Perspective format transform with numeric pattern, text being capitalized by default for a previous discussion on this topic / problem.
However, the big problem is that a Text Field component has no idea about numeric values and restrictions on legal characters. That means that
105.32 kPa
105 .32 kPa
10.5.32 kPa
105.32kPa
105,32 kPa
would all be accepted.
The Numeric Entry Field component
- will only accept numbers and the decimal separator.
- has a spinner option.
- has input bounds.
- has a built-in format option.
- three mode options.
- an invalid-entry style option (e.g. red-border if you go out of range).
- will align numbers to the right (although this can be overridden).
But the real deal is that your method is creating a string that can't be output back to a numeric tag type. Also, visually, displaying the units in an editable field suggests that they can be edited. I don't know why the other software you refer to would support this.
Finally - it just looks right!