I understand that you don't want to add features to make web sites with construct 2, and I don't want to ask you to add any features like that, but that's not the issue here - the issue is that it works perfectly upon exporting, but not when previewing. It's not really adding any features, it's just making it consistent with the exported version that works properly. Surely consistency between the preview and the exported version is a good thing!
Also, I've considered the things you've mentioned and depending on the website, I don't think most of them are that much of an issue. I can have a starter page that checks for HTML five support, and redirects the browser to the proper page. In this way, I end up having the benefits of having a normal HTML version and an HTML five version so all browsers can view the content properly in one way or another. Also, some pages don't really need forward and back if all the content is on one page. The page I'm designing is like that, and also doesn't have much text content for search engines to crawl through anyway.