This kind of topic make me wander why some people express same amount of hate like Brock in DP is receiving toward Misty character and Johto?
Acting like Whirl Cup was all she did being "useless background". When thats far from true doing more in that saga than given credit for, got engaging development in second half of it and bringing lot of entertainment value by herself .
Or immense hatred for poor Iris in BW blaming all issues from that saga writing on her character? Despite having imo pretty unique background, refreshing goals to achieve and dynamic personality.
Personally i never hated Brock, so DP wasn't exception. In fact i never hated any character in pokemon show. Did some irritated me or caused disappointment failing to meet my standards? Yes, but never to the point of developing such negativoty and disgust toward character that i could not stand him/her.
Problem with DP i guess was that writers reduced Brock involvement in episodes even more than it was case with previous sagas(for role Brock obtained i was fine with focus he got in OS and AG not feeling left out and being able to say how his presence left some impact on those respective sagas). But in Sinnoh he was rarely involved within action. Having opportunity in passing his knowledge about pokemon relationships, battles or strategies to Ash friends(something which he did with Misty especially in havbing several things in common but to visible extent May too in having some quality moments spent togwther allowing that their friendship ferments and gain more substance with time). And proviode helping hand to other companions in helping defeat villains, deal with dangerous pokemon or in how to come up with strategy to defeat opponent.
Being more so disappointed than anything else of writers making balanced, more stable division of screen time between all three main cast members rather than just select two(Ash and Dawn). Providing new way through which Brock character could remain proactive and eventful to follow. In changing his role from someone who taught Ash about pokemon and battling while navigationg, cooking and taking care of their pokemon. In character whose past, career and motives would be explored more, being able to coexist with Ash and Dawn as important asset to main cast. Backbone on which younger , more inexperienced trainers like Dawn could rely and learn new things from him. While moving things forward with his own dream of becoming top breeder.
Or if production staff still wanted to have him become doctor, at least dedicate some set of episodes, arc revolved aropund Brock selfquestioning. Trying to consult with other people and decide whats best for his future, rather than jamming everything in last few episodes. Being rushed and too incoherent.
But at end of the day that was more so writers fault of not utilizing Brock more missing on opportunities to make better use of his character, than anything else.
EDIT:
PS. I see people saying Brock should had been removed sooner because he "overstayed its welcome".
But what does exactly mean overstaying your welcome?
To have character for who vewers feel he no longer produce anything productive to other main characters and storyline losing its significance? To cause people get bored of its antics and personality?
Or to give out imression how his potential was run dry not having room to be developed more?
Because people who grew sick of Brock wanting him gone overlook fact how there exists other side of coin. Fans which still liked Brock, enjoyed in his characterization, humor, flaws, quirks and habits. Wanting him to stay in anime and have writers do justice with character.
Fans who feel Brock had juice left in himself to offer more on table and could receive development more engaging and of higher quality if writers invested more energy and effort in breaking mold with Brock character. Learn more about his history, have him go through some struggles or personal issues he may had suppressed from past bringing new dimension to character.
And receive bigger importance to play in pokemon journey.
Its often forgotten how not all feel the same and how not everyone is happy with main characters being replaced wantingto see writers rather doing better job in keeping cast fresh and interesting. Passing through more substasntial growth and gaining new depth to themselves.
Instead of being replaced and forgotten about.