I’m not sure that your hypothesis is universally accurate, as beholders vary wildly in appearance and anatomy. I suspect that while many beholders haphazardly release millions of nearly helpless spawn, gleefully devouring any of the revolting little parasites that remain near their lairs, beholders reaching the end of their lifespan carefully select and groom their “heirs”. These creatures kill all but a handful of their spawn, and then select one from the surviving remnant to survive. Invariably choosing the beholderling that looks most like them, they shape their descendant to be their exact double. Upon the death of the elder orb, the spawn generally devours its ancestor. A few keep the dead beholder around as a memento, hollowing it out like a gruesome piñata.
While it may be true that beholders have more in common with starfish and other invertebrates than is commonly supposed, that sidesteps the burning question of what sort of “Luv Shack” a beholder would prefer. I have this image of walls covered with shag carpet (padding, in case the reproductive activities of the orbs grow too frenzied) with multicolored disco balls providing suggestive illumination. Enslaved minstrels playing Barry Manilow’s greatest hits (Mandy, anyone?) complete the terrifying picture…