Because I do. I'm working on a set of tests for an article comparing TOP, MAX & ROW_NUMBER. I have a simple data structure and I need a bunch of data in order to create my tests. I wanted that data to be distributed a certain way, to mimic some production system behavior I've seen in the past. Last night I got it all set by mucking about with the seed values of the various columns to get it just right and load up millions of rows in only a few minutes and doing this all on my lap top. Great tool!
I just received word from Rachel Hawley over at RedGate that SQL Data Generator has been released. I've been using the beta over the last few months and I've found it incredibly useful for setting up tests and playing around with my database designs, seeing how different data loads will be distributed through the indexes, etc. It's quick to use but fairly powerful and flexible and, frankly, pretty inexpensive. I strongly recommend it.