When Yakezie started the Wisebread ranking was based on Alexa. And if you get into the <200k range, you will be one of the top 100 blogs, which would translate to more advertising as wisebread top 100 was widely referred by the advertisers. But wisebread changed their ranking system. As 200k was a good rank to achieve, it just stayed with Yakezie. That would be the history of 200k :)
If you want to know what "you" will achieve with 200k – only what you make out of it. Some people say they got more advertisers coming in at that range. May be they are looking up somewhere that doesn't lists my blog, I have never had an advertiser contact me when I fell within that range. For a lot of really big companies – think Visa directly coming to you to advertise… they look for # of visitors and/or page views, for the SEO companies (sidebar ads, sponsored posts) they look for your PR (and if you push Moz).
The beauty of Alexa is that it is "workable". PR is pretty much out of your control. And by building Alexa you will be building relationship with other bloggers (as it registers only users with the toolbar, mostly other bloggers). So as Yakezie's main theme was building relationship that was an ideal rank to work towards. If you have already achieved that rank, keep building relationship and move on to other metrics – traffic, RSS, twitter… whichever you feel like.
That is my 2c. Looks more like a dollar though :)