1. Fake Profiles
Everywhere I go now, there are so many fake accounts/bots. Not all apps have photo verification. It's not like it used to be, sadly.
2. Time Wasters
Everywhere I go, a lot of people are "on it for a laugh". Kind of sad how there are those time wasters to whom all this is just a game, they don't realize that some people actually are looking for something. To prevent that, you could of course go for a paid service, like match.com as them "just here for a laugh" type people wouldn't pay for "just a laugh", but then again, some feel like not risking wasting money on a service for just a chance to get a match.
3. Lack of Feedback System
I believe that a feedback system would make things far better. She doesn't respond after matching with you? Give her 1/5 stars. She replies but keeps leading you on and then saying she isn't into you (mixed signs)? Give her 2/5 stars. She responds but takes years to reply? Give her 3/5 stars. She responds and is nice to you, but she doesn't give off many signs? Give her 4/5 stars. She responds, is nice to you and you went on a date with her? Give her 5/5 stars (obviously these are all just examples. Different people have different ways of rating people). Just think about it, if Tinder for example, went from a crappy system where it depends on how many "Likes" the person has accumulated, to a feedback system, where people can vote on the person... the difference is that those likes are a first impression, while the feedback system actually reveals what the person is really like. To add to that, the like system makes sure that hotter people have an exponential rise in score theoretically (until there are no more people left to like you) which should actually be prevented in order to provide everyone an equal chance at matching.
4. Lack of Games
I believe games can actually add a bit of fun, reveal more about someone's personality, make your intentions more clear, and overall a potential ice breaker. A pretty great example is draugas.lt, they have four games that I know of, "Want to meet?" where a person is shown to you and you have to say yes/no to each, "I want to" where a person is shown and you can choose the likes of "have coffee together", "give massage", etc, "Be my" where a person is shown and you have to choose what you think of the person when you see them, for example, "Sun", "Cherry", etc and "Choose a couple" where two people are shown and you have to say whether you think they look like a great couple or not. And obviously the answers aren't revealed to the other person yet, they have to either pay or play 10 cards to reveal what was said about them. So as you can see, games like this can be implemented and can improve connection between people, reveal your motive (relationship, hook up, etc) and act as an ice breaker.
5. The Ability to Verify if the Person is Real
So far, the only app where you can verify if the person you are talking to is real, is Bumble (if not counting apps like Hot or Not which actually state on the profile if the profile is verified or not).
Any points that I missed, let me know :D