Kevin OQuinn
AC Team Emeritus
Offering a 16 GB version lets them keep the base cost down. Adding a microSD slot lets people who need more storage get it, and adding the slot costs little. That's what I expect as a base model, but hopefully they'll offer a 32GB model, too.
"We" actually don't know the cost of adding the sd card slot. If you want NTFS support, there's a licensing fee for that. I would be curious to know how much engineering time/energy is put in to making sure it functions the way it's expected to as well.
Either way, now that official support is back in Android manufacturers have decided that cost/benefit is good enough to put resources in to including one. Considering Moto released a version of the G that has a slot, odds are good that this new X will have one as well.