Is it in best interests of the software development industry for one framework, browser or language to win the war and become the de facto standard? On one side it takes away the challenges of cross platform, but it opens it up for a single point of failure. Would it also result in a stagnation of innovation, or would it allow the industry to focus on more important things (whatever those might be).
I believe whenever there is only 1 option, it will definitely stagnate innovation. If all we had was 1 language, then we wouldn't be able to solve anything but what that language was designed to solve.
Imperative languages like Java and C# solve a certain set of problems pretty well, but it also helps to think in a functional manner sometimes, such as with Haskell and Lisp.
Furthermore, cross platform issues are not an issue if you are talking about a web application, because you control the hardware and software (note, I am talking of the server side code of course, the browser cross platform issue is separate).
Paul Graham wrote a great essay on how the Web lets you as a developer use the tool you think will solve the problem best.
No. Competition is good. It may make a web developers job easier, but I think it's bad for the industry. I personally prefer having choices.
I believe Joel Spolsky's technique of creating his own language (Wasabi) to insulate his company from being platform specific is a good one. I also believe it is a good idea to use products that accomplish similar things that are more targeted at specific problems like JQuery.
I'm gonna have to agree with Mike on this one and say that without competition there is very little incentive to innovate.
Defacto standards are bad because they are usually controlled by a single party. What is best for the industry is for there to be a foundation of open standards on top of which everyone can compete.
The web is a perfect example. When IE won the browser war, it stagnated for years, and is only just now starting to improve because it's hemorrhaging marketshare. The Netscape years prior to that weren't much better. The CSS 2.1 standard was released ten years ago and still isn't supported well. As a consequence, web development is a Black Art of hacks and work-arounds to get websites to render consistently.
My job would be a hundred times easier if I could build a website according to web standards and be confident it would display correctly. Just think of all the cool things we could have been working on instead of fixing IE's rendering errors.