"Good Thing" is often capitalized, or as above italicized, for emphasis in hacker circles. The idea is that it's established jargon [1] suggesting more specific meaning than a casual goodness remark (whether that's true or not, I'll let you decide). The TM is another such intensifier, with the informal meaning of "distinctive or characteristic", rather than literally trade-marked.
It's very much the inverse of making a statement like /replacing all domain specific languages with bike shed driven development/ would be a bad thing™
