Why don't any DSLR cameras have a video mode?

I was thinking of buying the Nikon D3000 and I liked everything about it but the only thing keeping me from buying this camera is the fact that it can't record any videos. I want to have a camera that takes sharper pictures, with manual settings and all but also is capable of recording videos. I read online why some people think DSLRs don't have a video mode but it's all too confusing for me to understand since I'm not very knowledgeable in cameras.

Added (1). Is the quality really good in the nikon DSLRs that offer video recording?

There are several dslr models that do video. One that I own is the Canon eos t1i - clear, crisp HD
video.

There are other Canon and Nikon models available as well. They're not cheap, start at about $650 but they are out there if you want them.

The following Nikon dSLR's have a video feature

D3100, D5000, D5100, D90, D7000, D300s and D3s

Almost all new DSLRs have video recording. Where do you get your information?