I expect some of it is probably related to fear...
If the product looks like something that someone would use in an office, the kids will worry that it's not really designed for gaming and therefore might be a liability in that context.
It is intuitive to think that something that has been designed for a particular purpose will be more suited to that purpose than something that is not. Even though this is, in many ways, not the case for keyboards, it is a natural thought, and thus likely to be far more widespread than anything that requires actual information. Next, if something looks like it's designed for use in an office, then the kids will worry that, regardless of what the marketing says, the product has been designed for use in an office and not for gaming. Once again, it's a natural thought that can easily occur when information is absent: if you have one product that, judging only by looks, could only be for gaming, and another one that could be for gaming or office, the first will seem like less of a risk.