Originally, these protected bubbles had protected platforms on-top of them, creating a design whereby the liquids would be sifted through the platforms and poured onto the surface from the spawn platform. It was a provisional method used to deal with the issue of griefers who poured liquids in the spawn region. However, now that these platforms have been removed, what is the point of these bubble blocks? Although there have been no griefers who utilized liquids as of recent, the potential of damage by liquids is an issue that should be dealt with nevertheless.
Unless there are other reasonable options that are being considered or pursued, I recommend reinstating the old spawn platform design.