Yes, in future incarnations of the hardware, it would be good if Synology could add an option for RAM expansion. Either using full-sized SDRAM/DDRSDRAM (whatever-have-you) or the smaller and more expensive SODIMM. Perhaps on the other side of the hardware, installed laptop-style (ie, parallel to the mainboard)
RAM is always useful for people, you can never have enough for it, even for a Linux box! A full-featured box like the DS could certainly benefit from more RAM.