Are L2s Beneficial or a Drain?

I've heard some talk that L2s are not good for Ethereum. In the past, Ethereum was upgraded under the assumption the demand would be so great for block space that L2s would be needed and the L1 would just be used to secure the L2s. However, it seems that L2s get all the block space without actually enhancing the L1, what they receive in security far outweighs what Ethereum gains by supporting the L2. Is this an accurate analysis and, if so, how should Ethereum go about solving the imbalance? Should we "tariff" L2s? Should we somehow make them share in their profit more? Or are the L1 and L2s already living in harmony?