To respond to the opening question, I actually have a friend (my room mate specifically)who I have been trying to get into D&D. She is a big video gamer but she also sometimes enjoys RPing(like freeform on forums and stuff). I tried my darndest to get her into 5th edition D&D. We went to Adventurers League together for a bit and I even DMed a HotDQ for a few weeks(before life stressed me out too much to continue DMing). After an initial session where she had a great time and really enjoyed her introduction to TTRPGs, she steadily started becoming less enthusiastic over time. She got bored from the lack of mechanical complexity to 5e(which I share with her at times). It felt like a lot of combats devolved into "I attack" "I attack" "I attack" style gameplay. 5e seems to have a kind of scale of complexity for classes and I tried to sell her on playing a full caster, but she absolutely loves playing archer characters in fantasy games and was absolutely deadset on always playing a Ranger. Although this might be a bit of conjecture suggesting she may have done it on purpose, when her fiance demanded more of her time she completely gave up D&D in exchange for still being able to raid. She told me about her problems with D&D and I took that opportunity to tell her the good news of 4th edition. She told me she is never going to touch 5e again and wants to play 4e the next time she plays D&D.
I wouldn't go so far as to answer the question "why does 5e suck?" since 5e having problems in my opinion doesn't make it "suck". However, I have a lot of problems with 5e as it exists currently.
1) Vast differences in class complexity. There are classes I won't even touch in 5e because of lack of combat options. I mean normally I'm a caster player in D&D so even in 4e I played a caster most of the time, but where as in 4e that choice was made because I preferred the controller playstyle and often preferred the imagery and aesthetics and fluff of flashy robe wearing types in 5e that decision is made because full casters are the only characters that don't bore me to death. At least in 4e I would sometimes play non-casters/non-psion types.
2) Strong and clear connections between fluff and mechanics. One of the few things that caused my heart to sink in my chest when I first got my copy of my 5e PHB was three letters: V, S, and M. Where as before the fluff wasn't concrete and I had a lot of freedom to interpret what it looked like when my Wizard cast a spell, I was now absolutely 100% forced by mechanics to have jazz hands and jibber jabber(and bat guano) as part of my character even if I think finger waggling and chanting magic words and throwing around bat
is the absolutely dumbest thing ever and hurts my image of my character in my mind. Not to mention actual forms for Druids getting actual hard mechanical rules instead of having a nebulous concept of an animal form and you getting to fluff what it is within certain restrictions hurts my ability to play Druids. Hell, I used the 4e Druid class to play a vampire with reflavoring with out hurting my roleplaying experience. Now if I wanted to do the same thing in 5e, it would break down as soon as wolf type creatures started being eclipsed by higher CR creatures.
3) Overlapping of mechanics. It's funny how many different characters of different classes I can make in 5e where almost all of my 1st level spell slots are used to cast Sleep for the first couple of levels of the game before they graduate into Hold Person as their primary thing.
4) Lack of classes/races. I don't expect every class ever made ever in a previous edition to be available at release, but two of my absolute favorite classes(i.e. Psion and Vampire) were not only not in core materials but (due to the incredibly secretive release schedule) may not even be available in the near future. You wonder out loud if your favorite classes are going to be updated and suddenly people come out of the woodwork to cry about "rules bloat".
5) Super Oberoni Simulator 5000. I don't know how many times I've seen one of those phonies in the Facebook groups tell someone just to house rule something even when it's not exactly an appropriate response to the situation. That stuff really kills me. How about WotC actually gives us some more materials to work with and then people who don't like the materials choose not to use them instead of expecting us to finish building the goddarn game for them? That kills me. It really does.
