You're understating what they offer. With a Galaxy device you're getting essentially the best screen on the market (in both black levels, contrast, white balance and colour accuracy), the best camera (front and back), one of the fastest phones, and one of the most feature rich in terms of software features (split screen multitasking is a must), not to mention other decent little touches like getting a Wolfson DAC (audiophiles will appreciate that), built in wireless charging etc.
Naturally the loss of sd card slot and removable battery are definite negatives, but the phones are much nicer looking as a result. It's a trade off, and I can understand why not everyone appreciates it, but there's more to their devices than just that.
The odder detail is that they are not offering a 128GB version to compensate. I suppose if we had sales data for the 128GB Note 4 and the additional cost of the 128GB flash storage phones, it would make more sense. Then again, there was a SD card slot available on the Note 4.
Moreover, more consumers are moving and utilising cloud storage and higher data contacts.