In theory, it's a way to talk to someone every day. It truly forces us to keep contact with that person every day. However, Snapchat Streaks have removed the genuinity of having a real conversation. Sending selfies or just pictures of someone does not count as a genuine conversation.
Snapchat filters are just a reminder of our insecurities. Snapchat filters are especially great for when we aren't wearing makeup because we can hide our insecurities behind a fiter. But since Snapchat is also common among young girls, I think it also teaches them to just cover up their natural beauty, which makes them develop these insecurities earlier on.
Stress. The hourglass we get when a streak is about to break causes a great amount of stress that can be easily eliminated. Just thinking about it gives me anxiety. The text we may send someone that says "omg save the streak." No No No. No more of that. I am guilty. It's fine, we are going to stop.
Snapchatting just to Snapchat is ridiculous, and a waste of time. Snapchatting your best friend is necessary -- yes, keep your streak with her. But NO, there is no need to have a streak with a random mutual friend.
Sending a "streak" is just dumb. When thinking about it, sending a picture to someone to increase the number of days you've been talking is just kind of dumb.
If you want to have a genuine friendship or relationship with someone, you should just focus on having those fun or deep conversations, instead of Snapchatting. I don't think Snapchat Streaks should altogether be eliminated, but I do think that the unnecessary streaks can go.