Sometimes it can be difficult to find a good "sweet spot" when choosing cooldowns for groups of similar items such as those obtained through Archaeology. We don't want all the cooldowns to be exactly the same,
And we don't want cool downs at all - but sometimes you just gotta do what you gotta do - so reduce them, ok?
but we also don't want it to feel like the numbers were chosen totally at random. We may not always get the values right initially, so knowing what feels good to you and what doesn't -- and why-- is really helpful.
Especially with Archaeology items, most feel the skill is taunting (and insulting) it its total randomness requiring nothing in the way of skill only time (I've been digging every day since a week after release and still haven't found what I'm looking for - fun - on yeah).
And then when you do come across some little gizmo that might be amusing, it has ridiculous cool down, so you feel that yet again Blizzard is taunting you: "Dance for us slave"
I think if its something that transforms your look there shouldn't be any cooldown on it - why in gods name would there be?
I don't know what the thinking behind the cool down on the scarabs was, if it was because someone feared too many players would summon them all the time and lag a server, well that seems a bit unlikely it takes a long time to get so few would have it for one thing, and those who have one can still coordinate an "attack" and all summon their scarabs at the same time.
If there is some sort of server crash fear i suppose it should have a delay, but generally i see no reason at all for any gimmick items to have any kind of cooldown on them - with the possible exception of the trainset smasher, since the people who build train sets arguably have a right to annoy the rest of us for a couple of minutes.