I'm going to preface this by saying read my entire post before making a judgment.
When I came into K-Pop Super Junior and Big Bang were groups that I listened to frequently. I had an android app for which allowed me to download YT videos for offline viewing for which I did with Suju, Big Bang, and 2NE1 mvs. I must have had listened to Forever With You (Big Bang ft Park Bom) a million times.. What I'm saying is that I had a strong attachment to Big Bang, especially Seungri. So when I say Seungri leaving BB effected me the most it was the combination of his immoral actions which caused him being displaced that was just so unreal.
Yes, it was a disappointed when Hyolyn left, but she was making a decision that was right for her and Sistar ended on a high note and I can listen to Lonely on a loop without feeling sad. Same with Hoya.
With Seungri it was just another level of emotion that I can't even explain. Sort of like a combination of loss and disgust. Sort of like how when you love a movie from your youth and then it comes out that the director or producer that filmed it was doing disgusting and violative things to the cast and crew. Like how Joss Whedon verbally abused Charisma Carpenter on Buffy and Angel... and even tried to coerce her into having an abortion. But I digress.