1. They've revealed their intentions of data-mining and hence can no longer be trusted. I value my privacy and security and will never install their software on my computer; they can change their ToS all they want.
So, basically you're ready for ME3, but not ready for Origin I see. It's up to you. But if ME3 was on Steam, would you buy it? The thing is Steam can also scan your computer's hardware and I believe some of the installed software. That general Steam users hardware survey they do I know is something optional but I'm not sure if Steam still doesn't scan anything "in the background".
In any case, pretty much agreeing with RavenSEAL, almost any types of electronics today including software installed on desktop or laptop computers do in some way or another "identify" you and puts you on-line and tracks some of "your information" without necessarily asking your permission to do so. I mean just having Internet itself, being subscribed to any Internet Service Provider and accessing the web itself via any browser already sends some of your information on-line to God knows where and to/for whom.
You won't exactly find stuff about you by doing a search on Google though, it's not that kind of display of information that we speak of but it's more about gathering of data/information about "you" or "your computer" over time in some servers or whatever that can be and is sometimes used I guess. I don't know much about all of that but I certainly don't feel completely anonymous when I'm on-line doing whatever, regardless of video gaming, EA or Origin, or even Steam and Valve. There's no angels out there it's all about business, money, information (power), data-gathering and things along those lines, especially since the past five years or so with streaming/clouding and integrating social-meeting software in electronics left and right, such as Facebook being almost everywhere, Twitter, Google, etc.
Of course, you have the last word on everything concerning purchases, they won't force you to use Origin nor to buy ME3, be it BioWare or EA themselves. But what I'm trying to say basically is that even if you don't install Origin it doesn't mean that some of your information already circulates somewhere "out there" on the web from usage of any other types of software not even related to gaming. If you use your credit card for example, or PayPal or whatever other services on-line, heck just browsing the web and having an ISP is enough for some of your information to be stored somewhere, and could be used "for" or "against" you if need be, not always asking you beforehand to do so.
Anyway, more on-topic (related to ME3 specifically regardless of Origin), I'm ready, I can hardly wait... but I just don't quite have the money to buy it on day one unfortunately. I won't wait for it to be on Steam since... well... I don't think it'll ever be available on Steam at all, I hope I'm wrong though. But by the time it could be on Steam I think I'll own it anyway. I'll buy it maybe two or three weeks after release, at which point maybe one or two patches will have been released and the day one DLC stuff will be something of the past.