>A developer may also fail in communicating how much time will something take
Estimation is not a communication skill.
>explaining clearly to pm why is feature harder to implement
A PM is probably not interested and does not need to know why they just need to know that it is hard to implement. I've typically done that by assigning a number (1, 3, 5, etc.) to a story indicating its difficulty.
If your communication problems extend to not being able to state numbers then you do not have a lack of soft skills, you have crippling brain damage.
>He may be unable to explain why more time for refactoring
Developers usually don't have to explain to other developers why more time is needed for refactoring, showing them the code in need of a refactor is usually enough.
PMs may ask why but they don't need to why and they probably don't care why anyway.
>It is not possible to write specs completely without ambiguity - just like no one writes code without bugs.
And? Going over to the PM and asking them to clarify a few details isn't exactly the hardest part of a developer's job. Average levels of communication skills suffice. It only becomes challenging when the PM writes horrendously ambiguous specs.
