Perhaps you forgot "USB" means interface standard for storage and "SSD" means chip standard for storage. "Stick" type storage devices are typically far smaller than "drive" type storage devices.
But both traditional USB stick devices and 2.5-inch or 3.5-inch form factor of SSD devices are made of NAND chips. So they are both SSDs.
What makes traditional HDD and SSD devices much bigger and heavier than traditional USB stick devices is density and NAND evolution made density improved.
It should be very much possible to make USB 3.0 devices look more like coins, pencils, mice, credit cards, watchs, or any other things than sticks. The only main components in making portable SSDs are connectors, chips for controlling and storing data, and a board for holding and linking such connectors and chips. Most SSDs of today are based on 2.5-inch form factor not because the chips are too big, but because laptop market segment using only 2.5-inch bay was considered to be the first major target market for the early generations of SSDs. You can make SSDs in 1.8-inch or 1.0-inch form factor.
The Lexar drive is a little faster than average among latest-generation USB 3.0 devices. But it is not the only offering such speeds. My point was it is priced too high for such speeds. The price might have been justified two years ago when there were very few USB 3.0 stick drives in the retail market. I was one of the early users of such drives.
So, is there any reason not to have a US$30 product of similar performance, similar capacity, similar portability, etc.? Just what would have to make such devices so costly to produce?