The other thing to consider about Golden Ages is that if you have a state religion and access to Pacifism and Caste system, you can finish one with more Great People than you started with. Sure, you're not getting more Great People so much as you're getting earlier Great People, but it's a nice side effect from the Music Artist or the Taj.
Bulbing a tech and trading it around, or using Great People to bulb something that gives you a major advantage (Liberalism or Machinery, say) are great moves in the early to mid game. In the late game, it's not really that thrilling to get a Great Scientist anymore ("Oh look, I can bulb 34% of this tech!"). When you're working 300-odd tiles, Golden Ages' +1 hammer and +1 Commerce per tile, x multipliers, x 8 turns, really adds up. And there's free civic changes on top of that.