I believe the key problem is the high visibility of profile pictures, which makes it easy to stick to unrealistically high expectations for the physical attractiveness of people you're willing to talk with. This is reinforced by the constant stream of pictures - when you're swiping right on the couple of really attractive people every 15-20 profiles, it's much easier to swipe left on people who aren't unattractive to you, but just don't reach that level "ok this person is super hot". In other words, "super interesting and decent-looking", while traditionally a good combination, probably doesn't do particularly well on dating apps.
The 80/20 problem, then, comes from the fact that guys swipe right more often than girls, so girls end up matching with a ton of top 20% great-looking guys and feel no need to swipe on the other 80% of guys even though they often never have conversations that go anywhere (at least that's my impression from seeing the smokin hot dudes that my girl friends match with). To be honest, this seems fine for hookups, where you mostly care about physical appearance / attraction. But for longer relationships, I think there's a real lack of effective "modern" options.
What I'd like to see is an app where you don't get to see any pictures until you've initiated a conversation (of some minimum length) with a person. So while browsing profiles, you just get a short bio and some demographic information. I also personally think it'd be nice to filter for certain broad categories (education - for example, same school for college-age folks, income, ethnicity, etc), because intuitively I think people tend to end up with people from similar overall backgrounds - but I can see how that could cause problems. Regardless, I think an app where you at least don't see photos of the person you're talking to until a certain amount of conversation would be great. It would deal with a number of issues:
1. the 80/20 problem with respect getting any kind of conversation going is largely solved, as I believe that stems from people having profile pictures to quickly decide yes/no
2. by showing photos at some point, you still take into account the importance of physical attraction, but this time a person's image is backed by some level of existing rapport
3. you make a higher commitment to each person you talk to since you have to talk a certain amount to see what they look like
4. you're more likely to match with people who have shared values and interests since you have to actually talk with them
5. people are more likely to send messages since without pictures, there's never a feeling of "oh this person is out of my league, no point sending a message"
It's not perfect but I think it'd be a good start for non-hookup dating apps compared to the current choices. (if you agree with my thoughts and have some spare time pls feel free to make something like that haha)
[1] https://medium.com/@worstonlinedater/tinder-experiments-ii-g... (not really a rigorous study but the reasoning makes sense)