Neither extreme is good, a balance must be found and only the market knows where the line is.
Initially the common storage is cheap, and people will use it to store low-value data. As more applications emerge and more users join, the need for ckbytes rises and people must bid for limited supply. Those who use the storage for high-value data are willing to pay more than those who use it for low-value data. Low-value data will gradually be forced to layer 2, L1 value-density will rise.
The economic pressure means the ecosystem will not grow unlimitedly on layer 1, unlike on blockchains which abuse global consensus and common storage. Instead the ecosystem will grow horizontally and vertically simultaneously, with layer 1 always in healthy condition. The market will apportion storage usage and transaction processing on different layers dynamically.