Well, I've been thinking myself about why this question gets to me and why it seems so important.

If life's purpose where to be happy, what living is left when you can just take a pill to achieve that?

In fact, assuming we don't have to worry about earning enough money for shelter, feeding and medication, why does it rubs me the wrong way to conceive of a life that's little more than being a happy vegetable eternally hooked on a happiness-inducing drug?

"Induced happiness" is indiscernible from any other kind of happiness.

In brief, think back on your most joyous occasion in life. That moment where you couldn't feel better, that moment you cherish because, regardless of what was achieved (or how), it brought a great feeling of satisfaction with your own self. Now imagine being able to feel that great by simply taking a pill every day.

So, if you can achieve Nirvana in such an easy, accessible way, what possible motivation would there be to do anything else?

From a logical stand-point, it seems hard to say "we shouldn't do that," yet I just don't feel comfortable with the concept of living that way.