It's not wrong, because it's not the entire solution. I forgot to add that you also determine fees by checking every 2016 blocks what the average fees per block were. Now miners can't manipulate the fee anymore because they don't know who will find the next block, well unless they unanimously decided to insert fees enough to raise the limit, something really hard to achieve since if just one big miner doesn't agree the rest would be paying him to raise the limit.
Is this software design by debate? Am I the design oracle which will only tell you when a design is no good, so you search for the solution by suggesting all the things which are not the solution?

Think a little harder on this. This fails because its costless and obviously in all miners interest to mine fake fees. Fees are paid to this block, not the next block, miners would pay fees to themselves and skew up the average. Your revised proposal is isomorphic to straight up having miners vote on it, which fails for all the previously discussed reasons.
Yeah.. nvm me, a non dev noob.

I thought about it a bit more after I went to bed last night and it occurred to me what you're saying

I just wasn't sure if a miner can add a tx with some outrages fee that he doesn't need to broadcast while "looking" for a block. If he doesn't 1 miner alone could skew the average above that limit.
Well good luck to Bitcoin and all of us because I now really think we're going to need it if we are to find a solution that will scale and will provide the right incentives.