Starting work on an updated version with more "modern" api's and nodejs support, but this will take time (and therefor money). So, donations are appreciated, and opening up bounties on issues ( ) will help a lot. So will the couple of advertisements I put on the site.
There are a couple of reasons. First, consider that quite often the data one wants in an excel file is the same data that is on the screen. If it's already there, why have the server fetch the same information and then burn through some CPU/IO/RAM time to build an excel file from it, and then serve it back to the user? Seems a bit.. ridiculous doesn't it?
Heck, if you've been in the development business for more than 5 years, you probably have realized that some of your 'powerful' first webservers are vastly outpaced by today's laptop. I know that my first webserver was slower than my phone is now!
Here's the tricky part. There are a couple different ways of doing this, so pick the one that is least painful.
Combining some of these approaches seems like a noteworthy goal.. perhaps a script in the future to do so?
Dual - MIT and GPLv3. Use whatever is appropriate in your project.