Which auto-conversions are done has been a matter of much debate. The available options are those where the conversion is absolutely unambiguous. However, for cases where there are multiple things you could conceivably be going for the choice was made to not do the auto-conversion.
In your Object → String … which function do you think it should automatically pick?
We may well have missed one or two that should be supported, and are certainly open to reconsidering some others. One idea that has been tossed around but hasn’t made it up the priority stack/gotten enough buy-in is in the case where there is ambiguity pop up a small context menu to pick which to use. Do you think that would be an improvement? Or do you think we should pick the most likely and have people who don’t get the behavior they were expecting update the automatically placed node?