Yes I agree completely with everything you just said. I would have LOVED a storyline like this for Felicity and seeing as I am a very vocal Felicity disliker who doesn’t really like seeing her on my screen in any capacity whatsoever, that is saying something lol
In regards to Fitz and his storyline on Agents of SHIELD, let me preface this by saying that I am not by any means a fan of Fitz (just check out his "Anti" tag on my Tumblr page lol) but I definitely agree with you that Fitz’s brain damage plotline was such a important aspect of his characterization and it really allowed him to struggle in ways that he has never really struggled before which is something they should have done with Felicity. Also in Agents of SHIELD, through Fitz’s brain damage, he was hallucinating Simmons and the Simmons he was seeing was a manifestation of his own subconscious so they could have even had those scenes with goth/emo hacker Felicity and the real Felicity like they had in the Arrow episode after she got paralyzed and was trying to help the team. Except, instead of her making mistakes because her painkillers were making her hazy or whatever, it would be her brain damage manifesting itself by messing with her intelligence, reasoning skills, etc. which would have been much more interesting and also more suspenseful because it really changes the dynamic of the team and what Felicity is capable of doing to still remain a part of the team.
The Bones episode which I referenced in my previous post, which just aired a couple of days ago on Tuesday, did a similar storyline with Dr. Brennan and she had this amazing statement: “I mean, so much of my life, my intelligence is all I've had. You know, I ... I may not have had a family, but I understood things that nobody else could. My ... my brain, the way I think, is who I am. Who I was. Now I ... I don't know ... I'm ... I don't know anything, Booth. I mean If the thing that made me, me is gone? Who am I?” I absolutely adored this scene and I think it would have worked so well with Felicity since it would have showed even more of a struggle than her being paralyzed would have because like I mentioned in my previous post, she’s not like Oliver, Diggle, Laurel, Thea, etc. and going out and fighting crime and needing to go from being a hero by being physical and then doing a nonphysical role. Her role on the team is and always will be nonphysical and other than needing to wheel around instead of running around to do her hacking and whatnot, her role did not change at all. Messing with her intelligence and what makes Felicity the person she is would have been 1000x more powerful IMO.
Like as much as I really dislike Felicity’s character it makes me so angry to think that she could have had a storyline as powerful as the ones Fitz and Brennan went through rather than paralyzing her, putting her in a wheelchair (which was obviously done solely to draw parallels with her and Babs because Guggs was pissed they wouldn’t let him make her Oracle lbh here) then after only a couple of episodes of her “struggling” giving her some magic chip to walk again and having her get out of the wheelchair and walk in heels with no help at all. Like if they were trying to show her “struggle” they failed miserably because she looked like a Mary Sue all over again lmao