The reason why I advocate Ruby is straightforward : it's what the cutting edge Web developers use. When I coined the term WITA, I wanted to emphasize that this was a Web integrated architecture - not an IP integrated architecture. By integration, I mean integration of culture - the way that the community approaches, understands and tackles problems. In order for telephony to spiral into the much larger market of the Web, and therefore into the Enterprise, it needs to be introduced into the culture of Web development. Ruby is the prime ambassador for this, especially on the cutting edge of development.
This will, undoubtedly, cause major headaches for telecom engineers, who by-and-large have no experience with Ruby. (Maybe this is the Karmic payback, as the Ruby developers have no experience with phones). However, when the Web mindset is adopted and understood, then Ruby becomes a natural language for its implementation and development. In time, it may become the lingua franca of Web development; certainly Web development over time will become the definition of programming and architecture. The successful implementation of WITA applications will require the adoption of this mindset. Personally, I have pushed myself down the Ruby road primarily for culture - so that I can learn Web development in it's native tongue.
I feel there is no point where this is clearer to me than when I consider IMS. As an architecture, IMS is clearly the son of the companies that advocate it: big vendors making big equipment for big carriers with big budgets. It is a product of the culture of carrier based telecom development. The essential issue is that IMS, although making claims to enable the deployment of innovative services, makes the implementation of new applications nearly impossible because of culture. It is unreasonable to think that development of high value, niche applications is served by ever larger architectures. It is implausible to think that, with a ratio of nearly ten Web developers to one telecom developer, that the web developers will toss Ruby for P-SCSFs and HLRs. I recall a conversation with Henry Sinnreich a few years ago, where he said that he loved SBCs, as they hastened the demise of carriers because they were wasting their money purchasing them, instead of deploying pure SIP networks. I wonder if IMS has sent him into some sort of Nirvana.
Ruby is about culture. WITA is about deploying telephony architectures where that culture rules.