Short Term Morale Boost
I used to feel a higher wage and better benefits would encourage me to make more contributions to the company, and then I was promoted to management. Being promoted made me feel amazing. The position came with perks, a raise, and then the high wore off.
You give employees a raise, throw them a new perk, and their work contributions increase; but only for a short time. Even though a decent wage is needed, along with benefits and raises, you still need to find ways to make employees feel invaluable to the company and that their efforts matter. Without feelings of what you do matters, wages and benefits only induce short term results.