Ironically, Google actually has some really talented designers now, but the minimalist look has become part of the Google brand, and so all the designers now are constrained by user expectations of what Google should look like.
When you have dozens of designers that all want to leave their mark on the product, you end up with...dozens of features, none of which fit together quite right. Google is in that state right now. Microsoft is in a far worse state, where you have hundreds of PMs that each want to display their button as prominently as possible. This is what people make fun of as "design by committee".
Until 2010, Marissa was the sole gatekeeper of what could go onto the search results page. The result was that it was at least consistent, if minimalist and relatively unchanging. The other result was that she pissed off a whole bunch of other people by saying "no", brought Search to a virtual logjam, and made numerous talented people quit. That's the price of design consistency and a highly usable product for users; everyone who's not calling the shots ends up pretty disenchanted, and usually finds greener pastures. Steve Jobs played an analogous role at Apple Computer - it worked great while he was alive, but now there is a design vacuum that you're starting to see in their later products.
BTW, if you want to see what some of Google's design talent can do when freed from committees, check out the Doodles. In general there is just one artist responsible for each individual doodle, and it shows. (Some of the interactive ones have multiple people involved, but even then it's a small team with a single creative lead.) And the doodles generally have a reputation as being one of the most delightful parts of the site.
I think it is quite the opposite now. Google designers are TOLD to uphold similar design pattern on all Google products, which have the same features across all of them.
Seriously, why does gmail, google+, and google search should have a similar look? It just breaks some functionalities. These products are different and should not look alike. Pushing same patterns into users mouths, when it hinders the experience is an overkill.
... with an advanced understanding of graph theory, a research paper outlining a novel searching and ranking algorithm, a distributed cluster of servers crawling and indexing tens of millions of sites, and an inverted database of every keyword that appears on all of them. But yeah.