The premium set also gives a permanent triboost which does seem to have little effect if you only look at the buff in your playerinfo. However, this buff can actually really be felt when you're playing with non-premium players and keep talking about what you find (the exp can be seen as they were higher level when you started playing a session with them, at the end of the session you're the one who's higher level).
The material storage would indeed be very nice if they were added to the premium set. I don't feel bothered about it though. There are plenty of ways to gain the SG's needed for this storage. You can actually access it if you're a free to play player. I actually like that.
When it comes to the amount of character creations... why would you need more than one?
Besides trading and max client orders, there is more to the premium than stated by the OP. There's a triboost effect, access to premium storage, and access to Alliance Storage. I'm not sure if the mission pass is also part of the premium set, but I also received one after purchasing the premium set. The difference is pretty big between premium and non-premium imo. Big, but not so big that it's mandatory if you want to play the game properly. The only thing I hate about the premium is that non-premium aren't allowed to trade.