There's been 8GB phones released without SDcards as well.
I really think that it is more of a push for the cloud than a money saving thing.
Could carriers be paying money to manufacturers to geature less internal storage so as to encourage the user to use their data for cloud storage. inb4conspiracytheory
Another use for my MicroSD cards, Playstation 1 ROMS, Doesn't need fast storage (compared to the original CDs, MicroSD is plenty fast), but eats up a ton of storage. My smartphone basically acts as my sub-computer when I can't bring my laptop, so my usage benefits greatly from a MicroSD slot.
What I would really love to see though is a flash drive or memory card that can be used on the phone, and any PC out there without any sort of secondary adapters. Since my own phone runs Gingerbread, I can still directly access all it's contents via Mass Storage, making my phone suitable as a flash drive, but as I learned the hard way, this is not so with a lot of later phones (and is the reason data recovery is a PITA on internal storage of such phones

)