We don’t say b’ahavah (“in love”) before any other commandment – so why this one?
Probably because it is easier to be loving when affixing a mezuzah, hearing the shofar, reading the Megillah and so on – but when it comes to looking lovingly toward human beings and wishing them well with all one’s heart, it is much more difficult. They have their faults and failings; they also cause offence even if they don’t mean it.
Next question – when most of our prayers are in the plural, why is the Priestly Blessing in the singular?
The Chafetz Chayyim offers an answer, which links up with what we have just said about b’ahavah.
No kohen can be selective. He can’t say to himself or the community, “I bless my fellow Jews – with the exception of Mr Levy or Mrs Israel”. Everyone, every individual, warrants a blessing. They all have their faults, but if God loves them all, so should the kohen.