None of the complaints here are the fault of Ruby or Sinatra. One exception could be the trailing slashes complaint. The issue exists in really any web framework, though. Flask, for example, will give you the same hiccup.
I tend to defeat it in Flask with `app.url_map.strict_slashes = False`
> There are too many ways to access parameters
This is a bad thing? The framework gives you flexibility to build your program the way you want, and the way your specific problems might require.
> You will need much more than included
Well... yeah. This is not a batteries included tool for building websites end-to-end ... it's a simple way to map an HTTP request to Ruby.
> Rewriting www.yourpage.com to yourpage.com, or the other way around
> Serving your site over https
> Redirecting all http:// pages to https://
> Running tasks in the background
> Saving data in a database, and reading from it
These are definitely not responsibilities for an HTTP -> Ruby library and the first 3 are certainly responsibilities for your public-facing HTTP server (Nginx, etc...)