I always play with hard reqs because I think they interesting to play with, you have to plan some of settling spots. Especially as I like Terracota you have to choose nice productive spot with no water, at least with 2 hills (I play with only Domination victory, because I don't like short games, and I usually have most votes in WC and very high tourism so before my games were over too quick).
And I didn't play with light, so can't really compare them.
I mean that sometimes I have no choice but conquer some cities, because AI can be very annoying, aggressive or city has some Natural Wonder, strat resources or location and it just happen that those cities have some Wonders.
For example in current game as China - it's overpowered civ right now, because of it's new UI and I got very lucky with start location - lots of flat land without many hills or features I have built 20 wonders, and leading AI's have 8-10 Wonders. I took cities that had Pyramids, Macchu Picchu, Borobudur, Medicine Wheel, Skara Brae, Plain of Jars. I have conquered all Greece, but the city Argos, which has 4 Wonders, because Alexander declared war twice and was very aggressive with taking over my CS allies.
But what I mean is that before 3.0 Wonders more then 2 eras before didn't count at all and now they are counted forever with +20% increase in production costs. And that is a lot, before, I could plan that when I enter new era production cost will go down and now seems they don't go down at all.