Ash need Brock they are best friends and if he left ash would get lost and die of starvation
Explain how and why Ash and Misty survived the orange islands? I mean, being caught unprepared in terms of food and supplies in the middle of an Ocean is just as life-threatening as being caught unprepared in terms of food and supplies in a forest. Ash won't need brock to cook for him (If he was able to make it just fine in the Orange Islands without Brock cooking for him, he can be able to make it just fine without Brock in his journey.) Don't think that I want Brock oust from the series, since I feel he is fine, but the whole "he needs to be near him or else Ash would starve to death" is IMO a poor justification due to the Orange Islands.
Speaking of Brock, I found it a bit ironic that the writers seemingly "learned their lesson in regards to replacing Brock", and thus had him remain on the main cast for all eternity, and yet they forgot the huge complaints of the Orange Islands (which was one of the reasons as to why Brock even returned for Johto, anyways) when they replaced Misty at the end of Johto. I mean, If I were the writers, then I would think a million times before I would replace Misty due to the complaints in the OI season.
I mean, if they couldn't even replace a character with Brock's popularity level (whom, before Traceys arrival was considered to be one of the more unpopular characters in the series, according to a Japanese blog.) without getting hate mail and over a million complaints from the fanbase, what makes them think that replacing Misty, who is at LEAST 10x as popular as Brock according to TRAdmin, would be a success? It wouldn't, really, so it's obvious from that that the writers never really learned their lesson in terms of replacing characters.
(and Believe me when I say this, May had gotten huge complaints from the fanbase, moreso than even Tracey according to Fabuvinny, which is saying quite a lot, so I sincerely doubt that she is popular, and before anyone mentions her reappearance in Battle frontier, they also brought back Max (who is also unpopular, moreso than his sister, and possibly even the least popular now), so it can't be because she was popular since, if it was, they won't allow Max in due to the fact that he has a very small fanbase. No offense to May, Tracey, or Max fans, but I was trying to make a point.)
Anyways, thats all for now.