Chuck Lorre gutted what could have been a truly great Sitcom
The core of Two and half men was always family. About two brothers and how they raise the son. And had they stuck with the family motif the show would have had vast well spring of stories to branch off on.
Hell, I'll accept that Sheen left the show over disputes that may have nothing to do with the story lines but the best replacement for his character should have been another relative. With the addition of a cousin or uncle, some lost rich relative because someone has to be able to afford that beach house, Jake and Alan would have had a new dynamic to bounce off of but still had the same familiar feeling. While I would have created an older character, some long lost eccentric uncle, Kutcher playing a young cousin would have accomplished the same thing. But that character would have called Jake on his BS (in his kooky fashion) and gotten him to straighten up and maybe be a positive influence on Alan in some way. Maybe he has a heart to heart with Jake and says "I don't know you but I know you're a Harper and you're better than this." And just as Jake has a moment of reflection the doorbell rings and its two midget prostitutes dressed as dominatrixes and the three of them go up to Charlie's old room the cousin/uncle says "I'm keeping my eye on you, kid." A heartfelt moment and funny ribald bit and a call back to Charlie's debaucherous ways which is apparently a family trait all in one scene.
As it stood, Walden Schmidt had no real reason to keep putting up with Alan who had become increasingly opportunistic and manipulative in no appealing way whatsoever. We just had two characters stuck together because the show requires it more than an organic chemistry between the people.
Had the show continued on its family bond trajectory then the later seasons should have seen Jake developing a relationship with a girlfriend, maybe they go back and forth, on again off again but one step better than his commitment phobic uncle and control freak father. Jake whom they called stupid at every opportunity could have buckled down in high school and gone to college (barely) and really start to thrive there maybe due to the positive influence of his girlfriend. For the series finale, the show could have ended with Jake either graduating from college with a degree, getting married to his sweetheart or becoming a parent with his fiance or all of the above. The last line and shot in the show could have been Alan, a proud grandfather holding his grand son and posing with Jake and (cousin) Walden saying "look us, three and a half men.." freeze frame, fade to black.
This is why Jake's character should have been the backbone of the show. But all of that is academic at this point since Lorre had decided to keep rolling with his cash cow no matter what the cost to the show's spirit. The series finale was just a logical culmination of all the ridiculousness unfortunately.