People don't like Drago because he is polite, respectful, and treats Suzie well. Many players just want to see Suzie debauched, defiled, and dirtied. Drago isn't the man for that.
I think it's because Suzie feels so comfortable it feels safe for her, which is good but familiar. But for some other characters, like even the policeman, you see a different side of her. With Drago he's so 'respectful' and safe that you feel like she hasn't gone very far at all. I think this clashes with the sharing genre slightly because part of the excitement for Anon is something new, but you don't see as much of a 'new' reaction from Suzie as you do with other characters. He works more like a 'dipping your toes in' character, but eventually you grow past it if he doesn't change as well, which you don't expect because Suzie's a much stronger personality than he is.
Another example is with the boat captain catching Suzie, he's not disrespectful to her at all, but it works well because you see Suzie a bit caught off-guard with him. She always feels so comfortable with Drago that he feels like he's almost a slightly nervous dildo. I think the common theme is the uncertainty Suzie feels is much stronger with even small moments with other characters and other moments like sharing a number, taking pictures, so it makes more excitement and player anticipation.
Another thing is that he's respectful but much less assertive, so it feels a little bit like all the initiative is with Suzie with Drago, whereas with other characters Suzie is reactive to them taking initiative as well. Some of the other characters might push her or make a request or touch her and you don't know what she'll do, if she's willing to go that far, or if she will really like it. She might reject them like if she gets kissed on the beach, or she might be uncertain, or excited but nervous like with the request for pictures in the texts. But Drago takes less initiative than them so he's kind of like an intro-tier character.
Just my opinion