Maybe there are lots of earth-like planets with intelligent beings, but travel is impossible and communication is useless given the time delay.
It would cost a lot of money. It would take a very long time (hundreds of thousands of years). Nobody alive today would see the results. There are any number of systematic and non-systematic failures that could occur. building things that work autonomously for 100Kyears is nontrivial. Even if you succeeded- say, 100Kyears from now, one out of a thousand of your samples crash-lands onto a remote planet and revives- congratulations, you've maybe just contaminated an otherwise unknown ecosystem.
The story gets more interesting if earth has fusion, stable government and research funding, then you could make humans into tuns that can travel for 10K years, and have advanced propulsion (.01-.1c), pre-deliver full infrastructure...