Thank you for sharing your opinion.
I agree that using CSS hacks for taming browsers is a bad thing, however, some other aspects of front-end development come into consideration here:
1. Using more CSS files will lead to more HTTP requests to the server and slow down the rendering.
2. As far as I know, Internet Explorer can handle up to 32 CSS files, so if we have a page with 10-15 RadControls and each control requires more CSS files, we are really pushing to the limit.
3. We are in a constant process of improving the standards-compliance of our web controls and actually the number of "evil" CSS hacks used in our skins is diminishing. So having an additional CSS file for a couple of CSS rules is quite unnecessary.
4. Introducing a practice of having multiple CSS files for different browsers will have a rather demoralizing effect on web developers (I mean all developers using our products, not just us). Instead of trying to produce a cross-browser code, they will count on their ability to feed browsers with proprietary CSS.
5. This seems like a matter of personal taste, but in my opinion, managing one CSS file is easier than managing several ones. For example, you can put all CSS rules for a given HTML element one after another with comments and later easily gain a perspective what is going on.
I hope you find these points reasonable.
P.S. Concerning the IE7 skeletons, actually IE7 is a lot less troublesome than IE6, so in most cases we code for IE7+Firefox+Opera and use the "star html hack" or "underscore hack" for making IE6 behave properly.
the Telerik team