Where are the "Replacement Patterns" (Tokens) in "Set Data Value" in Rules? Most of the actions in Rules allow you to use tokens, but seemingly the most obvious place where this would be useful, "Set a data value," does not seem to support it. Am I missing something? It seems like it would be pretty trivial to add support for this, but I can't find in the code why, for example, the "title" field in "create a new entity" supports tokens, but "Set a data value" does not. Thanks!
It depends on the type of the selected target data whether tokens can be used for the value or not.

For example if the target is a simple text field (e.g. node:title) then the value can be specified with tokens. On the other hand, if the selected target is for example an entity (e.g. node:field-tags:0), then token input is not possible.

When working with formatted text, it is necessary to drill down to the value column of the field. E.g. for the node body, specify node:body:value.