The mod author of that mod forced you to use ships by removing the other methods, but balanced costs accordingly.
complete removal of other options is not needed at all in my opinion. But could be made an optional setting I guess.
Back then I unlocked capsule shooting before I added the mod, so I could still use it after installing that mod. It was nice to have and using both but not the rockets. Capsules still could only transport a few selected items and in low quantities, while spaceships were the true cargo transport. It was an interesting mix.
To allow spaceships to be actually sustainable at that much earlier point in game than originally intended the cost probably needed to be adjusted. Spaceships were so much later that the fuel costs were a no-brainer at the point were you actually unlock it, but using spaceships right away probably strains the limited supply of the earlier base too much. Also you were locked at the lowest ship size for quite a while as well and had to operate multiple ships because of that. the next ship size research was still where it was in the techtree if I remember correctly.