Any DLC that is made AFTER the release date is fine, it is the issue of creating this type of DLC for sale at launch meaning they're purposely keeping (important) parts of the game from people at the get-go. Now whether those parts play into the main story or not isn't really an argument, the character it self is a Prothean, just listening to its dialogue would be reason enough in it self.
Obviously the DLC with the Prothean is going to be really interesting, probably epic, because hey, people need to buy it extra PLUS its a friggin' Prothean, of course they're going to make something amazing, it isn't just some random human or race. Just wait and see until after release, the only other option would be that they're then purposely releasing a bad DLC, and why would they do that..
The Protheans are an extinct alien race which mysteriously vanished over 50,000 years ago. The only known space-faring species of their time, the Protheans arose from a single planet and developed an immense galaxy-wide empire. Not much is known about them, but many of their artifacts, ruins and technology have apparently survived the ages.
[...]
In addition to the technology they left behind, the Protheans left a greater influence through their in-depth study of other races. Their work has had the greatest impact on humans and the hanar. In humanity's case, the discovery of Prothean ruins on Mars, which were home to a small data cache, introduced humans to element zero and eventually revealed the location of the Charon Relay. A Prothean ruin on Eletania can also yield an ancient recording from a Prothean data recorder that was implanted into a Cro-Magnon human.
http://masseffect.wikia.com/wiki/ProtheanSo, combined, we have:- ACTA supporters
- Insane prices mimicking Activision
- Keeping content from people at launch
- Origin
The choice shouldn't really be hard.