Just watched the GDC with Ghostcrawler, Quick question about reworks

Ill try keep this short and to the point. I played Galio pretty heavily last season (took time off until this past week to start this season) and old Taric was one of my main champs. I'm curious if they were reworked because they were unpopular or because riot felt they were OP? or what i think it really is, is that they tend to be harder to play, Taric was a very niche pick. So when people picked them as a general pick they tended to perform poorly causing a bad experience for the team. Is this a correct assumption?

I felt both champs were actually pretty strong. Galio could have used some mana cost buffs and maybe some ult mobility but for the most part I felt his kit was fine. Taric i felt was actually really strong if you knew when to pick him. I still see games where i go "I really wish old Taric was a thing, he would be great here."

I guess the tldr version is: What is the decision making process about deciding that it is best to remove a champ and do a complete VGU vs just buffing or nerfing their current kit?

Is it popularity? ( I don't think so, it is okay to have unpopular champs that a small player base can relate to.)

is it OP kit that cant be balanced? ( i don't think this either, champs like blitz have a much harder kit to balance than say Taric did, although i'm sure this is more case by case. Ryze is probably often reworked because of this.)

is it people just tend to do bad on the champ in general even if the kit is actually fine? (If out of 1000 people 990 try Galio and suck with him and cause a bad experience for their team and say he is bad, but 10 play him a lot and figure him out and do well with him, is the kit really bad? (this is the answer I think you will say based on what i saw in the GDC talk).

Id love to have a conversation about this, game design is something that really interests me (even if i lack the programming skill set).

PS: unrelated question, do the designers of champs and kits and what not all know how to program or is theory and concepts the majority of the job and a separate programming team implements their thoughts?

@Ghostcrawler

-KingSapdeIX