Clearly it doesn't suck to be them, if the only inconvenience they have had is to support their colleagues during times they have needed it then they are not doing too badly.

Also (unfortunately) people who do not have kids, particularly women, are more likely to progress in their career as they have not taken any career breaks, so I guess that could be seen as an upside, though in my opinion is very unfair.

Overall I think companies should be there to support people when they need it, as a company you should plan your resources so people can take paternal / maternal leave, and also so that the other employees aren't overburdened because of it.