Re. 'breathy' voices -- I would imagine that Victorian corsetry would have a part to play in the end results for singers! Such constriction must have added a whole new array of technical difficulties, which would have mattered less for parlour singers who were unlikely to require decent projection.

But nowadays I would blame it on two things.

1) The inability to imagine a song as an unaccompanied thing, resulting in the addition of
    (all too often extraneous) accompaniment by several instruments.

2) The subsequent reliance on what is called 'microphone technique', which raises a whole
    other set of habits, many of which I personally find irritating!