The DLC's add a ton to the game. New storylines, new sectors (more space), new ships and buildings, new mechanics (in some), etc.
Do I think you need them all at the start? Probably not? I don't know how much things cost at this point since I've gotten all the DLC's when they came out since I got the game so it's hard for me to say whether it's "worth it" price wise. But just from a content and fun standpoint? They add a LOT to the game and are worth having for sure.
IMHO, the Split ships are the ones I prefer flying generally, so I would recommend that DLC if nothing else. But every faction has one or two ships that are best in class, it's balanced nicely that way. I just know that if I had to start the game from scratch without Split ships, I would be sad. :-D
I am completely enamored with Inkbound right now. Its a turn-based tactical roguelite by the guys who made Monster Train. It has a similar feel to the combat from Marvels Midnight Suns, which I loved also. It just came out of earl access recently.
Oh and they took out all the microtransactions in the game during EA. People complained and they listened! So there are some mechanics that look like, for example, a season pass, but it's free and automatic now. I think that's pretty awesome.
Anyways, game is fun. Devs are moral. Works in linux. A++