Yeah, sorry, that was the implied question that I sorta knew you were asking but ignored it because it's a hard question.
Since you already own the game yourself, I think you're probably in the best position to make that determination yourself, by actually trying and playing the game, and then thinking, would it be worth 13 bucks to you for every time you complete a tradition you get some big bonus perk, to be able to turn all your guys into psychics or robots? To be able to build a bunch of worlds to spread yourself across to giant resource spheres? I don't know how much 13 bucks is worth to you, but I do know if you don't enjoy the base game Utopia probably won't make you enjoy it more. And probably (unless you really love robots and killing organics) Synthetic dawn won't be worth the ten they are asking for either. If you do enjoy the base game, then they COULD be worth it too you, depending how how much you expect that much money to be worth and how much you'll enjoy doing the things they let you do. For me personally, I think Utopia was worth it because I like ascending and I like building megastructures, but since I don't like playing as robots that much, SD wasn't really worth it to me. But clearly other people have different, even opposite, opinions.
Also as I went back though this thread to look at what I said in the past about this (turns out my opinion wasn't really a valid answer for this particular question, unlucky me I had to actually think for a moment to make a new answer) I saw this question by EnigmaticHat addressed to me that I missed from back when we were talking about leader lifespan which caught my eye now.
Edit: Criptfiend, WTF are you feeding those guys? IME lifespan is *max* lifespan not average. I can be up to the repeatable lifespan tech and still have deaths at 75, sometimes earlier. Are you running the one planet strat and researching a new lifespan tech every 5 years?
What is IME lifespan? I don't know what that stands for, but lifespan in the game is based on a minimum, and there isn't any max (Or maybe there is a max at 8 and 1/3 years past minimum when the death chance reaches 100%? Not sure). The average is according to the wiki 5-6 years above the minimum.... I have no idea if that math is right, it feels like the average is closer to 2-3 above minimum, but idk. I have no idea how you can possibly be at repeatable lifespan tech and still have deaths at 75 unless you have both the short lived trait for that species and they are substance abusers. You start the game with almost that much lifespan, and a single lifespan increasing tech should push the minimum past that.
Uk-Ma was probably hired around 30 to 40 years old, and he's going to last minimally until 207, on average dying around 210. For something like 175 years of service. He's a bit of a stand out, having two lifespan extension traits (including magic space life tree maybe? I can't recall if I saw that this game or some other game) You can probably knock off 50 years off that for most of the others. 70ish for those that don't get any lifespan traits (although you can see that seven out of the nine on that screen have one). But even so, the minimal service without dying in action or to substance abuse is around 100 years, or living to about 150. I have no idea how one could have half that.
Va-Ra the admiral is probably worth noting as well, as he's only the second admiral I've ever hired and he's still going strong. He personally lead my fleet to take over around 80% of the galaxy, including beating off the crisis and two awakened fallen empires. And he's still not near death. He's certainly the posterboy for how you really don't need to replace organics that often.