Its just that record companys are more clued up, business wise.
Back in the day, artists were singers, musicians and performers long before they got in a recording studio, so IMHO the cream rose (the music exec's most common defence).
What happens now is the record company are so savvy that the whole package is sorted before it goes to press, musical talent is only a part of the whole saleable commodity with looks, personality etc.
You just need to look how much of a huge point they make of it when someone writes and records their own material, its always like theyre the new Lennon or Lady Day.
Its just that the job has changed, people like Legend,or even the Spice Girls or Westlife et al are just as professional at what they do. We just listen to music from a different era, not just musicaly, but on a business level too.
M