I'm sorry, I really want to defend Bioware, but this is just flat out stupid. I'm not wholly against the idea of Day 1 DLC, or DLC in general, as it has been said it's a good way to utilise the departments which wouldn't otherwise be working on the game near the end of the development cycle, even if it can come off as 'milk-y', it's perfectly legitimate. The idea of Bioware adding an extra character and mission as Day 1 DLC for those who think it is worth it is fine, but NOT this character. I have read quite a bit of the leaked script, and of all of the new squadmates in ME3 (I won't spoil the other one, although you probably will know by now), Prothy is the most vital to the plot, he adds the most to the game experience, he is an integral part of the lore and overall story of Mass Effect 3, he was written in to the plot right from the beginning and plays, if not an integral role, certainly one which deepens the general lore a great deal. He is the game's 'shock reveal' character, he is the big plot twist squadmate that changes the dynamic of the game hugely, the closest comparison would be Legion in ME2. Whilst not involved in plot events a great deal, he adds a major part to the team on both a lore (you know, being a frickin' Prothean) and gameplay (he is the only Vanguard in your squad) standpoint. Unlike, say, Zaeed or Kasumi, he is clearly meant to be in the game in the first place, he fills a hole in the game from a lore and gameplay perspective which would otherwise be left empty.
Essentially, what Bioware are saying at this point is 'herp derp, let's cut the most important new squadmate out of the game for everyone except people who dropped £60 on the Collector's Edition or are willing to spend another £7 having dropped £30-40 buying the game day 1, which would usually come out at around 90% of the people who buy the game overall, like cutting Legion out of the game for around 3 out of 3 and a half million of the people who bought the game, it's just ridiculous. ME2's Day 1 DLC (well, it was more week 1, but that's another story) was completely inoffensive because a) it was free for those who actually decided to support the guys making the game (needless to say online passes are something I personally support vehemently, but another topic for another time) and

it added next to nothing to the overally story or lore in general. There are far better alternatives to making people pay for the game's most important new squadmate, which BW have done before - make it free, for a start, even if you desperately oppose actually putting him in the game to begin with, it's just a flat out ridiculous notion that anyone would ever think this is a viable business strategy at the very least.
Am I going to boycott the game? Of course not, I believe I am a better person than to do that, to discredit all that Bioware have shown us of the game thus far, which I have very little qualms with, by denying them a purchase. Hell, I'm probably going to buy the DLC as soon as it's available, the ME series from a lore and universe standpoint is near untouchable, and any content which fleshes out said lore to this or in fact any degree is an automatic must-have, and the game just seems empty without it, to a small effect, given how it's integrated in the plot, but nonetheless putting content like this, specifically this especially, as Day 1 DLC is a really, really bad idea if they actually plan on having any trusting consumers after the fact.