1. Your reputation suffers when users encounter issues while using the browser that you don't support.
2. The support cost of "letting users try anyway" is non-zero, and probably significant.
However, they sometimes offer a "try anyway"-link and sometimes not. The times that I can not easily "try anyway" makes me dislike Google much more than the times that I "try anyway" and it ends up broken in funky ways.
Bottom line; Yes, your reputation suffers when users encounter issues. Your reputation also suffers when users encounter the big blocking issue of not being welcome at all.
Google are trying to keep existing users happy with the "try anyway" link. This is a new business, and they have decided they don't want to support IE.
At worst, this annoys die-hard IE users, but they're not your customers anyway.
The danger of adding a try anyway link is that people will click it, then still call and complain that your site doesn't work even if you place a huge disclaimer telling them IE is unsupported.
Finally, your website may do things that not only break in IE, but can cause your users to lose data when it does break. Yes, standard backups, never deleting data rules apply. But there is time spent either recovering, or explaining to users why you won't recover data for them.
(Don't take me for a Microsoft apologist, I still hate developing for IE7 and still have to do so daily. But the IE8+ (IE9+ if you rely on HTML5/CSS3 features as core elements) is really not that hard to work with.
* potentially lose work
* have a product that you paid for that doesn't do everything you want it to do
* get frustrated when things don't work and nobody will fix them ("Why don't you care?")
Bottom line - if you don't want to support Internet Explorer, I'd say feel free to detect it and then block it. Preferrably not via a referer string, but via something you can't change like one of Internet Explorer's own bugs/incompatibilities. Like, for example, detecting document.all, or via something proprietary or broken in IE.
Please don't do that, it will also break support in browsers which emulate that behavior for compatibility with IE-only websites. document.all is actually also there in Opera.
Their problem is that they want to be "pixel-perfect" across all browser. I get why, but as a User I don't really care as long as everything else works. And chance are that with IE9 and IE10 it will.
I'm not a IE user, but when we stop supporting IE6 we put a big sign saying that if there were problems we won't fix them and to download a modern browser. But people still went to the site even if some divs were in crazy places because basic function they needed worked and maybe they hadn't the chance of upgrading their browser.
If one of your client is once on another computer with only IE installed and doesn't have permission to install another browser, the fact that he can't use the website at all, is that a feature ?
https://github.com/h5bp/html5-boilerplate/blob/master/js/plu...
They are going to fail either way - it's better to fail gracefully, no?
What I'll have to say about it probably won't be positive.
If a choice of browsers breaks a modern accounting application, that's poor design, not a feature because an accounting app damn sure better not be relying on javascript's math capability.