The emphasis on defense in pro ball has gone up a lot in the last 10 years. Hitting is still most important but since advanced defensive stats are out there teams are emphasizing it a lot.
defensive stats are the reason Heyward got so much money. He is a solid hitter but 10 years ago a corner outfielder with a 115 ops+ would not have been that impressive. But his great defense combined with good but not great hitting makes him one of the best players of the league.
you have to hit to play in the majors but in all positions except first you need to field unless you absolutely mash. Defense can turn a slightly above average hitter into an all star caliber player and MLB is full of outstanding defensive players ( Simmons, machado, lindor, arenado...). IMO MLB defense is now much better than in the steroid era when all teams cared about was home runs.
i would say that the emphasis on hitting is bigger than 30 years ago but not as high as 15 years ago. You need to hit but if you are a HS third baseman that projects to be a 1B you will be drafted as a 1b which lowers your stock.
the 2015 top draft picks Swanson and Bregman don't project as great hitters ( they project as very good hitters but not as 30 bomb, .300 hitters) but they were drafted on top because they project to play a premium position well.