HYCHIKA® 17Pcs Bi-Metal Hole Saw Kit 

I came here for the same question. I do believe it's made like that so the bit does not over tighten and is hard to get back off. I think that's the only reason for it. Personally I'd rather not use it and have a tight fit if precision was needed. If not then a slightly sloppier of a hole is an alright trade off for easier accessibility (That's what she said)