So while yes, it's scary/crazy to launch a web app that is so easily clonable for Google, the "general use" nature of Google means that they'll never have these functions as prominent features. This leaves room for simple web apps who do a better job (or at least have a simple UI that is understandable).
Hmm. Why not? Why can't Google continuing builder richer and richer search results, results which become smarter and smarter in matching what users are looking for? The potential level of customisability for a search result/user to a search query is infinite. At higher levels you move beyond the crude "search" metaphor to what Google is really working towards: full brain-augmentation. Not a tool the mind must learn to use, but a tool built to work with the mind, a tool in fact that is tailored perfectly for each and every mind.
All joking aside it must be really hard work to keep your ranking at #1 when competitors (and google) can easily replicate your functionality.
If you provide the best product, even better than what google can provide, it won't matter that google put theirs at the top of their search results. e.g. G+ and facebook - no matter how hard google is promoting G+, it still hasn't gotten the traction of facebook.
Even with the google thing that does the function at the top, users have the choice. If it was a "I'm Feeling Lucky" style redirect (but always to a Google service with no search results page) whenever the query fit a format that keyed a Google-provided service, then the user wouldn't have the choice, but giving you a thing that provides what you think you want as well as links to other pages that might either do what you want or have the information you want doesn't deny you the choice of using those other pages instead of Google's tool.