The nature of form and business rules to only apply an outcome for when a logical test (set by the conditions) is true limits what is possible and leads to bloat.
For example, most situations requiring a form rule will have, at minimum, a true and a false outcome; let's say a simple single picklist field 'Delivery Required?' with 'Yes' and 'No' options. If a highly customised template is desired, there will be outcomes for whatever the end user selects: ie show and mandate 'Delivery Address' for Yes, or show and mandate 'Collection Site' for No. This would take at minimum 2 form rules in the current state of the application, with potential for additional rules being required for fields with numerous values/more complex customisation.
If there was functionality built in for IF/ ELIF /ELSE form and business rules, this would reduce the number of rules required to achieve the same outcome and allow for a much more sleek user experience which is easier to manage config-wise. I appreciate it might be a difficult feature to add, especially when considering adding multiple ELIF conditions/actions, but it would be highly beneficial for our instance.