Disagree with JMP (all three times).
If you do not shoot much 357 SIG, then by all means, it may not be worth reloading for you.
The bottle-neck, lubing issue isn't that big a deal. Using carbide dies, I can easily run 357 SIG through my Dillon 550 with just a light "dusting" of spray lube. I don't have to stop the process and get rid of the lube, either. Just spray at a 40-45 degree angle, don't use too much, and it works just fine.
If you do shoot a fair amount of 357 SIG, you stand to gain more in cost savings than any other defensive caliber. Plus, since it is a new caliber, there is a lot of room for experimentation and improvement on the "one size fits all" factory loads. In particular, I have had good luck with heavier 147 grain loads versus the factory 125 gr offerings.
If 357 SIG is just a passing experiment for you - like, those who got a 357 SIG barrel for their .40 S/W gun because they could - then maybe reloading 357 SIG doesn't make much sense.
But if it is one of your chosen calibers, it really isn't that much extra fuss to reload for it - especially considering how much $ you can save over factory ammo.