Personally, I find this ability a double-edged sword.
On the one hand, I find it particularly useful in knowing that the other person has read the message- at least it means that they received the message. It also prevents people from pulling the "Oh I never received the message (although I actually did and just didn't want to reply". Although arguably, there are still ways to pull that trick off by not opening the chat altogether.
However, on the other hand, it suddenly makes me feel all the more anxious when I've seen that the other person had "read" my message, however hasn't yet "replied". Did I write something really stupid? Did I accidentally offend them with my message? Maybe my message was too boring... did I come across as stiff? Perhaps I should've added some more emojis... or maybe at least had added a smiley emoji at the end of the message. Or maybe a laughing kaomoji to lighten up the mood? Maybe they don't want to chat with me anymore, and this is just them subtly hinting that they actually find our conversations boring, and want me to stop conversing with them. But was our conversation really that boring? I tried hard to make it sound interesting!! I DON'T UNDERSTAND WHY CAN'T YOU JUST REPLY. PLEASE.
I mean, I could write another message to attempt to continue the conversation, but I'VE BEEN DOING THAT FOR EVERY SINGLE TIME YOU'VE FAILED TO REPLY. Now I just seem desperate. I mean, okay, I am desperate... I want to know more about you. But I don't want to seem so desperate that I end up creeping you out or making you think that I'm just some sort of clingy creature okay?!
Why can't you be the one to start the conversation first.....you know, out of all the mini conversations we've had, there has only ever been two times when you messaged me first. And one didn't even count, because you did that out of obligation.
Wait. Didn't I just say that I didn't want to be the clingy type of person??? I mean, even my closest friends would start thinking that I hit my head on something if I told them that I've actually kept track of how many times you've started the conversation. I'VE TURNED INTO A CREEP AND IT'S ALL YOUR FAULT. (this is why tours of my particular brain should be forever restricted haha)
I know it sounds ridiculous, because obviously, chats aren't able to continue indefinitely (well, at least my chats have never lasted for an indefinite period of time). Of course, there is that huge possibility where I might've said something which no reply could lead to, but in the case where I think that I have left my message open for further replies--- you can bet that anxiousness creeps in fast.
Unless I really have no other choice (because all they've said is "bye" and my previous message to them was "bye"), I'll always attempt to write a reply as soon as I have "seen" a person's message.