1)There have already been a couple of high profile CRPG KS projects (Wasteland 2, Shadowrun Returns, arguably Dead State);
Not even close. WL2 is a guy with a license and unknown team. Fargo's last good game was released way too many moons ago and his team's last two games were disappointing. No recent track record, basically, unlike Obsidian that can back up their claim to glory with Kotor 2, MotB, New Vegas, Dead Money, etc. The talent is unquestionably there.
Sure, Fargo played KS well, but it's the power of the license, nostalgia, and
Avellone's name that propelled him to 3 mil. Shadowrun? Almost the same. Cool license, but who's making it? Dead State? You can't compare a single developer working with some ragtag indie crew with a proper studio and all star team. Not to mention that a TB zombie game isn't the same as a spiritual successor to the Infinity Engine games, which is a hell of a pitch. It's probably more powerful than the WL license.
Had Obsidian pitched some weird as fuck PST successor, only TB, I doubt they would have gotten as far.
2)Obsidian has an iffy reputation in the mainstream;
They don't need the mainstream. They need 50-100,000 backers to do spectacularly, mind-fucking-blowingly well. Do you think they can find that many among the BIS and Bioware fans, especially now that it's clear that Bioware had abandoned them?
3)Not even Cain or Avellone have the reputation, let alone charisma (which is important for the pitch video), of someone like Schafer;
Maybe, maybe not (see Fargo getting 500k on Avellone's name alone), but BG does and Obsidian knows it:
Obsidian Entertainment and our legendary game designers Chris Avellone, Tim Cain, and Josh Sawyer are excited to bring you a new role-playing game for the PC.
Project Eternity (working title) pays homage to the great Infinity Engine games of years past:
Baldur’s Gate,
Icewind Dale, and
Planescape: Torment.
4)Many people are kinda getting fed up with Kickstarter at this point.
Because they aren't interested in some small time shit. To do well, you need a popular brand, a name (or three), and a proven ability to deliver. Obsidian got all three and then some.