I see some SMT wire wound inductors are named like 3R3 or 4R5, much like a resistor, why so? I expected them to be like 4H5.
The "R" in the value doesn't stand for "resistance", it stands for "radix point". This makes the designation language-/localization-independent, since different regions use different symbols for the radix point, e.g. ".", ",", etc.