It's not that I don't wish to use them, I just don't like them being automatically added into the templates without any control - it seems to be the only thing that does get added in in this way.
Although I'm a great fan of convention over configuration I also like to be able to turn things off or control them manually if necessary (my perl is probably showing). Maybe a configuration option to disable the automatic behaviour coupled with a variable ($StyleSheets for example) that could be used to place them in the template manually? I might have a go at it myself if it really bugs me :).
We've just started to use SilverStripe in some live projects, and I must say that overall I'm very impressed with it. The quality of the design and programming seems to be a lot better than many of the other PHP projects I've seen. My only gripes are that it has it's own templating language (rather than using an existing mature system like Smarty or just inline PHP), and the lack of hierarchical URLs (e.g. /category/group/item) which makes dealing with large numbers of pages a bit awkward.