Well pitching improvements are a big reason why, so its not particularly fair to judge what worked in 1979 vs today. Part of the very reason why teams are selling out for power is because offense is down so if you are going to crack it, take the guaranteed runs cuz you cant count on those guys behind you to move you along, small ball you in or even get a hit, cuz pitchers are freaking nasty these days. So if you get a mistake , punish it.
That being said, Im not necessarily endorsing everything current - but I do err on the side of new school generally