Metro IE10 will be "Plug-In Free" (no Flash, no Silverlight)
appleinsider.com
appleinsider.com
If you have clicked inside a Flash-box then you can forget using the keyboard shortcuts your web browser offer.
Edit: I really think one shouldn't be able to down-vote without first writing a comment explaining why...
Then we get to html5. This is a part of the browser. The browser can suspend execution, ensure gestures work before the program responds or any other kind of integration.
As for mouse vs touch screen, I would find a flash site designed for a mouse quite annoying to use with a touch screen. Mouse environments are designed with elements close together, so you don't need to drag your mouse far. You can also use 'hover' effects, where your mouse hovers over an element. This is opposed to a touch screen, where I can easily move my hand/finger across the screen and can't 'hover' over elements. A touch screen also requires bigger hit targets, as you have less accuracy than a mouse.
Any reason for Flash not to work on touch based devices must be not also be applicable to other environments, like HTML5 or native, nor can such reasons be valid if they also apply to different kinds of hardware, for example desktop computers.
I don't have a tablet, nor access to one, so I hadn't thought of the swiping feature that was mentioned in another comment in this thread, which is one such reason. Flash's jail-like environment precludes cross-boundary swiping. Swiping is a feature that's almost unique to touch-based devices. Mouse gestures come close, but I don't believe they're widely used. The problems with it are also unique to browser plugins like Flash, because it does not exist in HTML5-based applications, nor native ones.
I'm having a hard time accepting that is the only reason, though. Is swiping really that important that it and it alone is enough to doom Flash and browser plugins in general?
This problem also exists for web apps heavily javascript driven, but seems to be less of a problem compared to flash apps. It's probably because flash apps are constrained in a small space so the interface needs to be more compact & hover driven.
What is more likely is that the user agent will be detected and that if it is determined that the user has no mouse that either some fall back mode will be used or that there will be an alternative UI preserving the basics will be presented, or a UI that will use the first 'tap' on the screen as a substitute for a hover.
The issue is probably common to all browser plugins.
Flash - as it is used on the web today - is difficult and unpleasant to use via touch. This is mostly due to the movies being optimised for mouse, not touch. If you include Flash in a new tablet, it certainly shouldn't be for its existing uses.
The fact that MS may abandon Silverlight and other Windows technologies is far more significant that the "look, look Apple are right again" angle.
How about CSS3 text-shadow and a dozen other CSS3 rules?
IE9 is still holding back the web, especially since it won't run on XP at all.
I don't know about you, but I certainly can't afford to throw away 100k every year.
When reporting issues I often say "Can you upgrade your browser?" to which I get the reply "No, it's what the IT department put on all of the machines, I use (BrowserX) at home though."
I suspect this is common.
Welp. I know what browser I WON'T be using when Win8 lands.
I have an android tablet and an android phone. I rarely use flash, but when I do its when there's no alternative. It works crappily, but it beats sitting there and thinking "Oh well, I better go find a desktop."