Well, we've had years of silence: Daishi simplied vanished after his failure, Hoshino barely replies to questions and just keeps posting ecchi costumes that costs 60 bucks. There was no hype built around a sequel, many people have lost faith a long time ago. Then they released that "please be patient" bomb, without anything else, then a poll. The hype was really low, yet it existed. Now people have hope for an announcement at E3, it is the right time to drop a huge bomb and then build the hype around it. Because trying to build hype around something that doesn't even exist isn't really rewarding.
I'm aboard the hype train for GW2: the expansion was announced in January, we had hype weeks, then the hype went down, then it was renewed, etc. They built their hype around something concrete, and I don't mind waiting till december until we get something (since we know the expansion was being worked on for more than 2 years).
So if SCVI was to be announced (at an early or late stage of development), it would help create a hype tht would barely ever go down if they know how to keep it up, even for more than a year.