Quote Originally Posted by liquidformat View Post
There are inherent issues with your premise that all creatures should have all slots. For starters let's look at giving a Vargouille a boot slot, this now means I can increase its non existent land speed by +10' while leaving no tracks in snow without worrying about slipping on ice. Please explain to me how these work? Or for another example giving glasses that provide dark vision to a blind creature, can it now see in the dark? Your argument falls apart because of very simple functional limitations of creatures, giving an armless creature 'gloves' now allows it to dual wield weapons with its nonexistent hands!

There is also the issue of sillyness, sure lets give the snake twelve item slots; that is hat, mask, necklace, torso, upper upper body band, upper body band, upper middle body band, middle body band, lower middle body band,upper lower body band, lower body band, and tail band. Does that not strike you as completely ridiculous?
Your examples are very good for demonstrating your view. On the other hand, there are things like Bracers of the Entangling Blast: deal half damage with a spell in order to entangle the affected creatures for 1d3 rounds, up to three times a day. That would be handy for a couatl and not problematic in any way, but a couatl doesn't have an arms slot to use them on. Instead of just having to commission a special version that's identical except for fitting a couatl, you need to pay double to get an item on an unusual slot. This seems awkward.

I'd take it on a case-by-case basis, personally.