I guess asking to create a package in a question would "need more focus", i.e., is too broad for the site. Converting an answer to a specific question into a generally applicable package is likely to be a lot of work, in providing sensible user commands, testing, writing documentation, and further maintainance.
Alternatively it could be argued that such a question is focused - writing a package is a lot of work but answering a question about writing a package can be quick (yes or no, possibly with some arguments in case of 'no'). However, in this case it is likely to be opinion-based, because the answer is "this is/is not a good idea because X". Also the voting on such a question would be problematic, it could be interpreted as a meta-style "upvote=support the request, downvote=disagree with the request", which means you could loose reputation not because the question is bad but because people disagree with you that a package should be created. Asking such a question on Meta itself is also not a good fit because Meta questions should be about the site only.
Both of the above arguments are reason for closure of such a question. Creating a tag therefore does not seem to be a good idea.
You could leave a comment under the answer to suggest the idea to the answerer. If they are interested then such a comment will be sufficient to initiate the process. Converting answers into packages has happened 73 times to date, see Which questions led to the creation of a new package?.