>>52872891You answered yourself.
Because it is not useful in gameplay, many people hate it. Some follow the above without knowing the reason, leading to the design being hated for no reason. Unless it's a cool ass dragon.
Design-wise, Meganium has two stamen-like antennae on top of its snout. Since stamens represent male flowers, it feels awkward to what was once named Chikorita (-ita is the feminine form of the Spanish suffix for something small or young). Many people will prefer Bayleef because of the leaf on top of its head. Only Meganium and Chikorita were kept from the demo to the final version, Bayleef came later, so this explains why Bayleef looks better. And don't forget, only the Chikorita line is retained, so its appearance is better than the other two starters.
Chikorita was voted #1 in Korea. Its popularity may be related to the Moonkorita(문코리타) meme. Thus, just because you see people around hating Chikorita doesn't mean the whole world hates it.