1) If you intend to make a profit off selling products available on the world market, no.
2) If you intend on selling "limited" weapons that are not available for purchase on the world market, then still probably not... though this is the best way of selling such products (no need to worry about market price discrepancies between what is needed to profit or spending limits for buyers). Of course, you'd be well advised to set a sensible sale price where you can profit even including cost of transport and others would be fine going through the trouble of space trading. However, I just don't think there is a large market for many of the limited products.
3) If you intend on having multiple empires on different worlds with the goal of having plenty of cargo shuttles to transport weapons stocks between worlds, then space is totally worth it.
These are opinions of course.