Yup. There may be thousands of earth like planets in our galaxy alone. Shouldn't we explore them some time in future ?
With 100 billion stars in the Milky Way, we're talking millions (or more), not thousands.
Making eradicating aging even more important.
Wouldn't it make more sense to live well wherever we are? I'm not saying we have to settle for Earth, but the focus should be on how people are living and not how many planets get checked off.
Living longer means signification rise in population on earth and given the unsustainable state of our planet, it makes more sense to look for other similar planets for habitation.
And if we invent faster than light travel in future it will be natural for people to leave earth in the spirit of exploration just like Europeans did to find the New World.