I had a pair of Hafler 200 bookshelf speakers all the time my 3 kids were growing up. Actually I got them when my oldest son was 2. I just gave them to a niece about 6 months ago, in perfect condition. They survived by first being hung from the ceiling for a few years, though by the time my youngest came around in 1991 they were back on stands.
The grills always stayed on. No curious looking round objects and an uninteresting box, combined with vigilance, seemed to preserve the speakers. I didn't have any subwoofer until they were all adults, but if I did it would be one of the SVS subs with the perforated steel grill like I have now.
Keep in perspective that the old Radio Shack Optimus speakers are not exactly "heirloom quality" items that need to be protected like a Ming vase. If they were mine and "something bad happened", I'd be like "oh well, guess it's upgrade time."