There is a ZeroClipboard feature request to use the HTML5 Clipboard APIs, where available, and seamlessly fall back to Flash elsewhere. Hallvord R. M. Steen, editor of the W3C Clipboard API spec, started working on it here:
I'm not the person you asked, but here's my reasons.
I'm on Linux and there no longer is a supported version of Flash by Adobe. (Apparently there is some NPAPI to Pepper bridge though, to get Chrome's Flash working in other browsers.)
I already uninstalled before that, because I wanted to force HTML5 for sites that dynamically switch between Flash and HTML5 and because I wanted to nudge more sites to support HTML5 by boosting the stats of people who don't have Flash installed.
> I'm on Linux and there no longer is a supported version of Flash by Adobe
I'm using Firefox on Ubuntu with Flash (flashplugin-installer) and it's still receiving updates. It's an older version, but it has been working fine with every Flash site I've visited so far.
I think everyone got most of my reasons covered below, but here they are: no need to manage updates, smaller security surface, battery life, fan noise. I typically browse with Firefox Nightly, and without flash installed globally I get HTML5 or whatever a site wants to offer me if I don't advertise flash compatibility. If I hit some must-have flash I have a key combo that opens the current tab in Chrome.
Historically, it's tended to have had far more zero day exploits than the web browsers themselves. removing Flash removes a huge attack surface, and 95% of the time you don't need it.
I don't have flash installed (usually using Safari and Firefox) and have to jump over to Chrome to use a site maybe once or twice a week, which is more than acceptable given the insecurity of Flash.
I really don't like flash. It's full of security holes and its primary uses annoy the living hell out of me. So I only use a browser that has it when it's on my terms.
An internal app we use at work requires an extension to do one button clipboard in Chrome and Firefox. And if you're using another browser, you're out of luck. I use it enough that I have the extension, but now the version we have and the extension it supports isn't "signed" in Firefox, so I have to make an about:config change.
We use clipboard.js in our product, it was the perfect replacement for flash copy. I highly recommend it, our users were none the wiser when we swapped it out.
Flash used to be the only thing that worked, cross-browser.
Chrome, I know for sure, changed their minds several times on whether they would allow it...security model thing, you could make it work only by tweaking some internal chrome setting.
The sales pitch at https://clipboardjs.com/ makes it sound like perhaps things have changed enough that a reasonable cross-browser solution is possible now.
My only regret with that would be that we use flash as a way to allow one-button copy to the clipboard (using this http://zeroclipboard.org/).
We had tried non-flash solutions, but none of them worked.
This sounds like it might work https://clipboardjs.com/, so I guess I'll be adding a backlog item to look at it.