Read somewhere that the eggs don’t contain embryos, and are pretty much only filled with goo until the moment it hatches.
Could they actually be “warping in” the young monsters from somewhere else? When a Monster hatches a minion, he’s rushing the process and thus only has enough energy and time to “hatch” a relatively weak minion instead of one of the big 4 we all know and love.
I’m assuming the eggs gather ambient energy and resources from the bohrium in the soil or something of that sort. The goo is displaced by the warping-in monster, mitigating the complications involved with warping into an atmosphere. Maybe it’s also a means of sending resources back to the main “hive”.
Hell, maybe everything’s stored in c-space until they are ready to be called in. That’s how the infestation spreads so rapidly - they don’t need to wait around for the monsters to grow. Someone stick a camera in one of those things.