woodie said:
you’ll have a backup lens or lens for shooting in less than ideal environments.
I'm also a Canon guy, but regardless of brand, a typical kit lens would likely be among my last choices in suboptimal shooting environments - if we are talking about dust and such - because the cheaper construction of the lens won't be sealed well against the elements.
If you need to shoot in that kind of environment regularly, you should be looking for a weather-resistant camera and would need a matched weather-resistant lens to go with it.
Without those, you'd need an encasement of some sort to protect the camera, at which point you are likely adding some kind of "filter" because of the need to keep the case sealed (something will already be in front of the lens) and the superior optics of a better lens would be that much more important -- plus it would be the job of the case to protect the gear...
Note that if dust or water penetrate the lens, it will enter the camera too through the mount.
EDIT: back when I bought my Canon EOS 30D, I got the slightly better version of kit lens with it, which is a 17-85mm. It is actually something of a mid-range lens rather than the normal "cheapie" kit lens that you'd usually get with a camera -- you can tell by the weight (decent lenses have some heft to them, both from the higher-quality materials used in the optics themselves and from the sturdier metal housings used to protect those optics)... I still use that regularly as my main "walk-around-and-shoot-whatever-comes-up" lens on that camera. I find that it is a good general focal length for "non-specific" shooting, and works rather well for me. If I am setting up a backdrop and lights with umbrellas and such, I'll generally try to use one of my prime lenses if I have one that will work in the room I have to set up in. If I'm standing in the back of a room and trying to shoot things at a drama, over the heads of an audience, I would likely swap in something with a bit more of a telephoto range. If you are trying to shoot birds... good luck! But a decent mid-range zoom like with a range like the one you indicated for that kit lens is probably as good a place to start as any (generic family/church/business/whatever walk-around events and the like), unless you do have something specific in mind... then figure out what you are missing and build from there.