I don't wish to be overly unkind Vadim, but I suspect 'gimmicky' is a something of a minority opinion.
Ok, I'd certainly accept that, as with HTML itself, its not a perfect model, but its rare that anything is. They are extremely useful, particularly when building larger sites, and sites where high level of dynamic, growing content are a feature.
They also offer a much simpler way to apply a certain level of automation/logic to the management of page format.
Having well designed and well managed style sheets as part of the core acs is a highly desirable thing. As ever, I'm sure great care and substantive thought will go into any such addition to the toolkit, as is most often the case here, and therefore I'm sure the benefits will be visible and universal.
Although I'd like to add that its not always the case the the 'lowest common denominator' approach is either wise or implicit, as you continually seem to suggest. Some companies, some indiviudals, some communities may genuinely find that the benefits of not appealing to all possible environments is outweighed by the possible negative aspects.
Take NN4.7. Lets face it... it was a *really* fussy and *really* inconsistent browser. Yes, you can do your best to cater for that browser and limit your resources, profitability and functionality if you want, but lets accept that whatever you do there are going to be thousands of sites that look shite in NN.7. Ultimately the user is going to change browser, rather than wait for a re-development of the entire internet.
It is important to cater for *choice* in terms of what your users can use as a browser, but it is not a question of a kind of moral obligation to support every browser under the sun. You provide the range of choice you feel acceptable to satisfy the majority of the community. I for one don't resent having had a 'push' to get off NN4.7 and discover the delights (and teeney footprint) of opera.
We'd be forgiven for having one or two little glitches on NN4.7, but we'd not get much thanks for a poor website on the most common of browsers...
I don't see that as defeatist, or poor design, its merely common sense and simple economics of organic processes