Ashley
I think it's moot to argue that running an executable is trusting the user to put faith into your executable. This has always been the case for any game, any program, anything downloaded off the internet. Windows' poor choice of default setting to prevent the lowest common denominator of user from being tricked, which will happen anyway for those people who blindly download and run software shouldn't detract from genuine applications using a system to its fullest by accessing as much privilege as they can. It'd be pretty sad if we were headed to a future where only "registered" developers get the privilege to have their applications actually use your computer to its fullest, and everyone else is forced to run through a non-essential protection layer or use a workaround/loophole like html5 that's supposed to make running the code seem "safe" because its the trusted browser running the code instead of a standalone application. Anyway, this isn't about Microsoft's bad choices, something i think everyone who'd understand agrees on.
If an exporter using SDL were made, the games would be cross platform, and genuinely perform well since the whole goal of SDL is to make things run everywhere. The license of SDL would completely allow this as well, and SDL would make things work 'everywhere', using the systems to their fullest, but of course i understand the work involved in making any kind of new exporter, i'm merely suggesting this as something that seems to mesh with your goals and provide the best of both worlds so to speak.
As for installing directX etc. This is something that's also to be expected when installing any kind of game. It's never been jarring to any PC user to see a directX prompt while installing a game, its been expected for years.
In anycase, im aware of that performance test, but rendering a ton of sprites faster isn't really impressive or incredibly important (of course it is a good thing). You admitted yourself that there aren't many optimizations to these aspects in classic, and they were never really necessary because the calculation of sprite vertices has never been a significant factor in affecting performance, games with 30 sprites on screen can have performance issues if you're doing enough with them. It's lovely that C2 makes many optimizations in order to squeeze as much performance out of html5 as it can, i'm fully aware of this and it is impressive that you get as much out of it as you do, but the fact remains that when i make a significant number of expressions run for enough objects, C2 seems to fall behind at least in my experience, but perhaps this has changed since i did my tests. You're fully aware that if you made the same optimizations in a native C++ engine like CC that you did in C2, the results of that tests would be completely different.
As long as everything's running in javascript, the performance is never going to be as good as it could be, javascript is simply much slower than any native C++ code and theres nothing that can change that. Theres benchmarks (http://www.i-programmer.info/news/86-browsers/3492-javascript-is-slow.html) you can find on the internet and floating point calculations will just always be significantly slower (http://stackoverflow.com/questions/17036059/javascript-is-4-times-faster-than-c, see comments), no matter how optimistic you are about it's future gains, and you've acknowledged this yourself.