[SPOILER] Text of cards leaked at worlds!

Probably because they didn't want to turn Weyland into a broken fast-advance monster, and you haven't considered the potential interaction with Jemison Aeronautics.

Let's see what would happen if Success was only a double.

Click 1: Install a 5/3 agenda.
Clicks 2-3: Play Success, sacrificing a hostile takeover, advancing your agenda twice. Then add 3 more advancement tokens on it from Jemison. Score it. Hope they had a clot installed before you started this click, because otherwise you just got 3 points.

Alternately:
Click 1: Install Government Takeover
Clicks 2-3: Play Success, sacrificing a 2/4 agenda, putting 9 advancement on the government takeover. Congrats. You just netted +4 points, and can now turn clicks into 3c at will.

So yeah... it's probably for the best if Success remains a triple. :P

(Fun bonus jank: Note that Success is ALSO the first card we've seen yet that actually ADVANCES things, rather than just places advancement tokens on them. This means that you could, in theory, use it to dump a bunch of advancement tokens on a Hollywood Renovation, which would then in turn dump a bunch of advancement tokens on something else.)

/r/Netrunner Thread Parent