Everyone hated those things back before people knew about the various ways to distinguish between HMCs, Water Worlds and ELWs. The shape of the little holo-image when you selected the planet as a nav destination helped tell the difference between HMCs and WW/ELW, and then people discovered the different sound effects when you zoom in on the system map. This was, of course, back in the pre-FSS days when you could see the whole map with just the honk.
Now, with the FSS, all ambiguity between the three "blue planet" classes is gone. Many explorers probably wouldn't even notice they'd found a "blue planet HMC" these days.