The international phonetic alphabet is mostly used as a transcription tool for phonetic notation. It’s not really used for communication purposes but more for representing sounds made at the various positions considered possible by the human mouth, to varying degrees of specificity (you can be more or less specific with it depending on what you are using IPA for). Most of the characters it uses are based in latin script but its purpose is mainly to make phonetic notations rather than be used for general writing purposes, generally each language benefits from having a writing system that suits its own particular qualities and using the IPA to write would not be very practical.

As for constructed languages, I think there is a lot of resistance to them among people in general at the moment, for a multitude of reasons, but I think they are an underexplored field that could benefit people some day. At the very least they are interesting to create, study, and speak. I do think natural languages are going to continue to be predominant for the foreseeable future and constructed languages will probably remain in the realm of idealists and niche hobbyists for a long time.