The key to higher Surface sales is...
1) Lets face it, The Surface distribution has been very limited so far, mainly to the US zone. The RT is only now expanding to other markets, other markets where Samsung and Apple have had strong retail presence for a long time now.
2) The US/UK market is a strong Apple-centric one. Breaking through the brand recognition of Apple is a tough sell. The focus should be on other markets where Microsoft can get easier penetration, just like Samsung and Nokia did.
3) Samsung's Galaxy phones were considered "meh" in the US for a long time. Its only when Samsung's strong distribution network in other markets (where Apple branding was not saturating the market) resulted in great sales that the American consumers took notice. The overall global success of Samsung driven by global markets helped get it recognition even in Apple saturated markets. Basically, nothing sells like success. I believe the narrative for the Galaxy changed only with the introduction of the S3 by which time Samsung had become a strong global player and this fuelled its positive perception in US too.
4) Another case in point is the Galaxy Note. Tech critics and reviewers laughed it off, until Samsung showed its phenomenal sales in Asian countries and others. Now no-one scoffs at the Note. Again, its global sales helped change its perception.
5) Nokia is again a prime example here. The Lumia has started to do well with 5.6 million Lumias sold in Q1. Out of this only 400,000 in the US. Again showing that even with all its marketing might its difficult to break through the US market. Nokia has started focussing on the global markets by bringing in cheaper Lumias and high end Lumias to the market quickly. Again its Nokias distribution to global markets that is fuelling its success even though it spends majority of its marketing muscle for the US.
6) One may argue that Asian markets are not a market for higher end devices and that only low-cost products sell. But I would disagree. Even the cheapest iPad costs $500 and the iPad Mini costs $400. And iPads sell in pretty good numbers. So does the iPhone 4S, 5, Galaxy S3 and S4. The market is limited for high end devices, but even a 5% of the market in India/China results in high absolute numbers.
To sum up, what Im trying to say is that, MSFT should focus more of its resources on getting a global reach for its Surface tablets. Overall higher sales for the Suface tablets will fuel a "perception" of success and will result in better sales even in the lucrative American market. The current strategy of an exclusive focus only on the American market will not help in driving sales or mind-share.