Transforming qualitative and quantitative data or methods

I can see how a large number of interviews and video can be compiled and analysed numerically (i.e. turning qualitative research into quantitative research), but is it not possible to turn quantitative research into qualitative research as well? For example, if I have heatmap or clickmap data, can I not used the information to create questionnaires or usability study design?

Why has it been suggested that you can turn qualitative data into quantitative data but not the other way around? Or that you can turn qualitative research into quantitative research but not the other way around? If so, what is the reason for this?

For example, if you collect a lot of qualitative data from survey questions about what people think about a product (e.g. 1 for very good and 7 for very bad), you might not be able to work out exactly how good the product is, but you can work out what percentage of people think it is very good.

On the other hand, if you collected metrics from a website that shows completion rate for tasks or conversion rate for goals, to what extent can you say that users find the website easy to use?