I've always thought a large part of Google's market share was Webmasters checking their rankings. Whenever an update occurs, Webmaster searches increase as they check their sites to see changes. SERPs have been changing almost constantly for the past few months, so these types of searches have probably increased.
Google instant, from what I understand, considers SERPs returned while people are still typing as a search; multi-word searches might generate more than one search in Google's opinion, when in reality it's just one person doing one search.
Poor results likely generate additional searches in order to find what the user really wants.
An increased market share or a higher number of searches isn't necessarily a good thing for Google, even that's the way they might spin it. It might not indicate a deeper desire for additional knowledge, it may be an indication of frustration for the Google search user because they aren't finding what they want. Not everyone wants to see Wikipedia, Amazon, etc. Most already know of those sites, and could go directly to them if that's what they wanted.
I think Google is losing sight of the very thing that made it popular: finding the unique pages that really provide the information users want. These pages often won't be perfect, and may have validation errors, or other signs of poor quality. Google has been so busy going after spam, pages with top heavy ads, punishing sites with bad links, etc., that many of those unique pages are now buried.
End users don't care about links to a site from "bad sites." They don't see those links and they don't know about them, they just care about finding the best page for their query. That page won't always be Wikipedia.