Does Straight Talk allow you to use your phone as a wi-fi hotspot nowadays? I believe this function has historically been blocked on Straight Talk, since they wanted you to purchase one of their own hotspot devices. If it's still blocked, that's at least one feature that is lacking. MVNOs often get deprioritized data speeds in congested areas or at high traffic times, so you'd need to test the speeds in those situations as well.
Video calling through the carrier is still a thing, although it's admittedly not used very often, and is limited to video calling between people on the same carrier. The problem with using other platforms is that the other person has to use the same app. I don't want to have to install Skype on my phone just because someone else prefers to video call me on that service.