I would like to use this product but it feels irresponsible to do so. Why are we still making technology that stores such personal information without data being encrypted end-2-end?
1. Do you want to be able to search your data? Full encryption would make it impossible.
2. This is why it's open source. If you need full privacy, download it and run it yourself.
This could be a tradeoff. But also, I have full disk encryption and an index I can search that is itself encrypted. Eventually doing this over internet wires will not be an issue, and may not be much of an issue for many already.
To your second point: indeed this could be run locally instead, if one is that concerned about storing sensitive information online