I would gladly answer your question, and I know Im going to get downvoted because I won't exactly answer it. So understandable if you downvote me for not providing an answer, all I want is to apologize coz I like actually providing productive answers.

I just want to apologize that Im not willing to invest time into re-iterating my thinking into "why I think signal is not 'fun' to use". I dont wanna invest my time into re-installing Signal, writing a list and an essay about it etc and then going back and forth with you.

It would require much effort from my time to do that and in detail and we would go back and forth, so I'm just here to apologize for not responding to your question because it's a great question. I always like to give detailed answers but just not willing to invest my time into this discussion for which Im sorry. I hope you get an answer from somebody else if someone else shares the same opinion.

For context, and why I'm judging Signal harshly, I'm a software engineer at Powerfactors, and used to be a Frontend developer, now I'm professionally a Backend engineer. And I've started as a Fullstack and Freelancer. So I kind of understand both sides and trying to understand the user as well. Like I try to understand users like my Grandmother, my mother, to a programmer or a graphic designer. I try to understand who the software is for, and how to make it appealing to them and useful.

I make my own Project which I re-iterated many times throughout the years to make user friendly and "fun" or easy to use or actually useful for clients to use. So when I use a piece of software I think in detail what could be done better and what could have gone bad from both frontend, backend, and UX/UI and I like the OSX/Apple philosophy on this one. That's as much as you're gonna get from me, Im NOT going to re-install Signal again and write a piece of list and essay coz I know this is gonna take much of my time, it's who I am, I like writing detailed essays and answers + (i accidentally deleted my last answer instead of clicking edit i clicked delete).

edit: Again, I wanna emphasize, your question is awesome, if somebody here is UX/UI specialist, or knows about user-experience in general for some reason, and has the time to invest, you have my blessing. I'm making the comparison between Telegram, WhatsApp etc. vs Signal for context and why my opinion is that Signal falls besides them. + As you can see I'm not "arguing in bad faith". Im here to discuss.:)