As you've pointed out, the reports won't work with a list of doubles, they require a list of records or classes.
And the reason we don't allow a list of primitives (strings, doubles, etc) is mostly because we didn't thought it could be useful, and nobody until now requested it either But now that we have one request, we will study if it can be done. I think the syntax for such a feature should be just <#Result>, but maybe there is a need to require something like <#result.value> or something like that for the report engine to like it.
The workaround as you probably already figured is to have a record with a single "data" field and then have a list instead of a list. But if you already have the existing list of doubles, filling one from the other is not very efficient.
As said, we'll see if it can be implemented, and I will let you know.