Not just a small phone, but an ergonomically shaped phone is missing from the market. It would be great to have devices again that you can cradle in your hand and slip into a small pocket. Thin slabs are nice on a display shelf, but they aren’t human-centered. Give me a phone with a curved and grippy back and a 5.x inch display.
These kind of apps should be flat rate, else the incentive is for the best matches to be hidden, waste their time, or otherwise keep people lonely so they pay for more months.