That's what it sounds like too me as well. Yeah its a legit last name but people wont call you bob ryder, you will be addressed as Ryder like its your first name. And then it will sound like one of those lame hollywood names that they give their kids to prove how different they are.
They should really just record several common first names into the voice acting, and limit the usage in dialogue to prevent an overburden on VO work.
Example: take 50 common male names, 50 common female, 25 gender neutral - and only use the first name in key scenes. So most characters will use Ryder, in the same way Shepard was used in the original trilogy, but there will be a few scenes (like in the romance scenes) where a character will have a short line using the first name. Maybe a love interest saying, "I'm here for you, [insert name]." It's not that hard for a few different VO actors to record "I'm here for you, [insert name]" 125 times with a couple of takes on each name. That's 250 takes of a line that takes two seconds - that's maybe a half day's work for the entire cast.
Also, I can see it being used early and late in the game when your character (which by all indications will be military) is recognized in a formal or military setting where they use the character's full name ("Lieutenant Commander Jane Ryder").
Even if it was only used a handful of times, I think the effect could be powerful in further cementing a player's feeling that they created a unique individual who shapes a galaxy.