C++ 11 : decltype behaviour of T and T& derivation [ behaviour distinction between both ]

int i = 12;

decltype(i) x4; // type is int

decltype((i)) x5; // type is int&

We know from C++ fundementals that i is lvaue already. now decltype(i) is equal to type of expression i which is natually int. Now as per spec/standard (i) is also an lvalue and decltype((i)) should also in some way inspect type of expression (i) which is lvalue and is same as i which is also lvalue. But why the standard suddenly requires T& type ?

This is very confusing. because if it was decltype((i)&) then I agree this means decltype of int& would have been much more clear and precise. I am a bit lost here as to why i and (i) both of which resolve to lvalue type result in different types of T and T&.