Even if you could transfer your consciousness into an immortal machine and stick it on a starship, if it takes billions of years to traverse the galaxy because the ship is so slow, that just isn't that practical: by the time you get to a far-away star system, the star might have gone nova, the planet you wanted to see destroyed somehow, the lifeforms there killed themselves in a nuclear war, etc. The milky way galaxy alone has changed a good amount in the last few billion years: Earth certainly didn't look anything like it does now 4 billion years ago. If it takes you that long to get anywhere, it'll really limit what you can see: you'll be facing the heat-death of the universe before you've gotten out of the galaxy. I see your estimate about Juno's speed, but remember, if you're actually trying to explore the galaxy, you aren't just going from point A to point B, you're going to take a very long, circuitous route so you can see lots of star systems. There's ~400M stars in this one galaxy alone; how long would it take a Juno-speed starship to see even half of those? As an analogy, it only takes me 3-4 days to drive from the east coast to California, but if I want to see every city of at least 25k people between here and there, it's going to be a much, much, much longer trip.