Many priests would like to wear black vestments for funerals – the traditional color for mourning (and historically the traditional liturgical color) – but for a number of reasons it is often difficult to do so. I do not intend to address those reasons here.
A good way to make some use of black, even if it is not possible or opportune to do so in church for the ceremony/Mass, is at the cemetery. I have used a black cemetery stole on a few different occasions (over my cassock/surplice) at the graveside with no difficulty. It’s usually a sadder time than the ceremony in church, and the black just makes sense.
Here is a nice example of a black cemetery stole. Interested priests can contact me for more info. (It is not for sale but I can tell you where to get one.)
Hopefully, through greater catechesis on death and funerals, people will start to have a better appreciation of healthy mourning and the symbols that support it. Where that is not yet the case, it is still possible to make some use of these traditional symbols and so move things in the right direction.