Another problem with internal polls is that you will have the point of view of those who make the feature, not the point of view of those who use it.
Imagine the calculator code was a mess compared to the rest of the project, it uses outdated libraries and updating would break it, it may have some security vulnerabilities, uses an unreasonable amount of resources and breaks the build system. No one wants to work with it. Ask whether it is a good idea and most people will say "no", hoping to get rid of that mess. In that context 70% is a very good number. If on the other hand, it is a feature people love working on, then 70% would be very bad indeed.
Imagine the calculator code was a mess compared to the rest of the project, it uses outdated libraries and updating would break it, it may have some security vulnerabilities, uses an unreasonable amount of resources and breaks the build system. No one wants to work with it. Ask whether it is a good idea and most people will say "no", hoping to get rid of that mess. In that context 70% is a very good number. If on the other hand, it is a feature people love working on, then 70% would be very bad indeed.