Support

No, for two major reasons.

First of all, we no longer live in the pre-2008 days where search engines would consider these two URLs to be duplicate. Therefore, there is no practical reason to do this kind of redirect.

Second, putting a blanket redirect of URLs without .html at the end can be extremely dangerous. The .html extension is not decorative; it tells Joomla to forcibly add format=html to the list of page URL parameters when routing the URL. This can be detrimental for extensions using URLs which do not have a file extension, but are supposed to return JSON, plain text, or other kinds of non-HTML data. Not to put too fine a point on it, but this kind of redirection royally screws up a lot of components, plugins, and modules. Same thing goes for the forced redirection on URLs without a .html extension. If you are using any extension which handles a post-back from an external service (e.g. integrations with payment processors, social media logins, email providers, etc) the forced redirection would count as a failure for the external service, breaking the integration.

There are many more subtle ways this kind of redirection can break your site.

Please don't consider it. It is a bad idea. It will break your site. Been there, done that, saw the problems, scrapped the feature :)