Malz is less interactive. Throws abilities onto you and then can walk away while you take lots of damage. That is the reason he is considered a problem by Riot.
Lulu's kit has more interactivity to it, how you trade with her in lane is very important to how the lane will go. And there are a number of ways to out-play her kit, unlike Malz.
All that aside, their kits are too different. One cannot compare kits in a vacuum.
Your entire argument revolves around this comparison saying people hate malz but lulu is 'fine' though often banned...? -> therefore Riot should revert a buff. This is very convoluted, disjointed, and provides no evidence. It is simply comparing objective opinions and generalizations about people's (unclear which people) opinions about the two champions.
I'm not saying they shouldn't nerf her, but you've got to present a better argument than that if you want your idea to be taken seriously.