Gratitude feels good - it's an emotion akin to joy, and love. When we feel grateful, we feel good. Our bodies are filled with endorphin-like chemicals, and our minds are open and receptive. It's fun to feel grateful! Try this, right now!
So your gratitude serves you well, and it also serves the world. Even if you're feeling grateful in general, say for a beautiful day, your emotional state benefits you, and in so doing will benefit the world.
I won't tell you that you 'should' feel grateful - that's just putting obligation and effort into it. But I will invite you to add your "thank you" to me here, in gratitude - because it feels good for your, it improves your life by bringing in what you desire and giving you awareness of it, and it serves the world!