grammar - What does のに at the end of a sentence mean?

does it have a similar meaning to "が、ので etc." which basically make the sentence "softer" and imply something that isn't stated but that should be obvious to the listener?

something like "though" in English.

2 examples:

• 彼が出て行けばいいのに。


• あの建物さえなければ、きれいな景色が見えるのに。

Answer

のに at the end of a sentence can be rendered as something like "if only it weren't the case that ~"

From your examples:

彼が出て行けばいいのに。 (Aw man, it would have been so good had he gone)

あの建物さえなければ、きれいな景色が見えるのに。 (If only that building weren't there, we could see the beautiful scenery)

A~ いいのに is a fairly common usage, "would have been good if [only] ~A"

It usually reflects a state of regret or longing, or an improvement that can be made on the scene or experience. Hope that helps.