You can't treat domain valuations as taking place in a vacuum.
Any value attributed to holylemon.com is because there used to be a site at that URL. And the popularity of that site had NOTHING to do with the words in the URL, but because it offered funny pictures, videos etc which people wanted to tell their friends about and come back to. So the previous owners of the website took a meaningless brand and created a bit of traction with it.
The problem with your tool is that there needs to be a human sitting behind it, accurately flipping a switch that says "This domain name is 1) 100% generic 2) brandable or 3) trading off an existing site" with a corresponding massive adjustment to the value returned for that domain name (I'd suggest an automatic $0 for domains in category 3)