With contact terminals on the shorter sides, multi-layer ceramic capacitors (MLCC) usually come in a non-square rectangular package. Thus, the device between the contacts is longer than wide ("long" MLCC). Say, a 0805 package is 2.0mm long and 1.25mm wide, having contacts on the 1.25mm wide side.
There are low-ESL caps where these contacts are put on the wider side instead, e.g., on the 2.0mm wide side on a 0805 ("short" MLCC). This creates shorter and wider electrodes inside the MLCC, thus reducing Ohmic resistance and ESL. Besides, it reduces the stress on the MLCC when bending the PCB. The wider cap can also tolerate greater force before cracking.
To sum up, "short" MLCCs seem to have only advantages over "long" ones. Why does the latter have the majority on the market? Is there something I'm missing?