It is actually a bit more complicated than that though none of the problems can't be overcome. If you delete a key you either need to splice out the corresponding array element or do an exists test when looping over the array. If you change a key's value should it then go to the end or stay put? I am not saying that it is isn't that simple in specific cases, but in general it is usually better to just use an already made wheel:

• Tie::IxHash
• Tie::Hash::Indexed
• Tie::InsertOrderHash
• Tie::LLHash