Try making a game using one of the 'fullscreen in browser' options. Then hit F11. In the top 3 major browsers, you're now playing in hardware-accelerated fullscreen. Fullscreen gaming is perfectly possible in HTML5. The main barrier is people aren't used to it - like you say you assume you need an EXE to play fullscreen, but it's perfectly possible to do it in a browser, you probably have just never hit F11 to play a fullscreen browser game before.
I'm aware that you can go fullscreen in browsers. Chrome seems to do it best, but still causes issues when the mouse hovers near the top of the screen (while testing my breakout clone, a little item scrolls onto the screen informing me that I can leave fullscreen by hitting F11 again... in the process I lose mouse control... and my ball sails right past the paddle... 1 life lost, thanks Chrome.)
Firefox's idea of fullscreen appears to include leaving a menubar at the top of the screen and the windows taskbar down the bottom... unless there's an option for "actual" fullscreen that I haven't found.
To be honest I haven't used Internet Explorer since the late 90's, so I'm not sure how it handles it.
Browsers always have been, and always will be quirky. There'll always be inconsistencies between the browsers, and I'll likely have to accommodate the fact that people will stick to their browser of choice, rather than the one that plays my game better. This is ironic, in that html5 games are supposed to be platform independent, but have become somewhat reliant on the browser they are being played in, merely moving the "platform" variable one step further along. Games will now run on a Mac and PC, as long as those Macs and PCs are running latest generation browsers. This is fine for certain things, but it's a trade off nonetheless.
The recent update that allows fullscreen zooming is pretty awesome, and I implemented it the second I updated, but even with the superior aspect ratio handling compared to CC, it still results in a game that is unreleasable because of issues running it within the browser environment. And my crisp and chunky pixel graphics are unavoidably blurred with the linear scaling that I can't turn off (I'm sure it will be possible to choose nearest neighbour in the future... maybe).
I understand and agree that focusing on html5 (at least for now) is the best choice for a small company with limited resources - putting those resources into the features that are likely to create mass appeal, and the ability to make games that have the least impediments to getting the gaming equivalent of "bums on seats" (I guess it's still bums on seats?)... realistically, browser games made in Construct2 are more likely to be played by the majority of people than the equivalent exe games, and it's quite true that the majority of people who use Construct to make games will only ever make small, short attention span type games. And maybe in the future, the distinction between operating system and web browser will be gone entirely... and everyone will be running a Chrome OS, and all apps will run inside, side by side and on top of the browser environment... even Construct will be a browser based application, and you'll be able to run browsers inside browsers!
Honestly, I don't think that revolution has happened yet, or is likely to happen quite so soon - and even if it would be awesome, I still hope the current generation of games aren't hobbled by being too far ahead of their time.
I'm all in favour of an Exe wrapper (essentially it would be an html5 browser that doesn't do anything except run the game, correct?) as a temporary work-around. As an optional plugin, I don't think your fears that people would be confused about it are anything to worry about assuming the exporter is clearly labelled as "HTML5 Application" or something along those lines. If it can get around some of the 3rd party browser hassles, then I'll beta test the bejesus out of it.
HTML5 is unlikely to ever out-perform a native EXE, so there's still a solid case to make an EXE exporter for performance reasons.
That goes without saying.
Also, thanks for staying in the conversation that I'm sure you're sick to hell of by now.