I think a lot of incidental tools are generated by focusing on your core business. For example, I work at an ISP. Something we do is generate Letters of Agreement for cross-connect at shared sites. This involves making a nice-looking PDF from some HTML that the customer's information is substituted into. So I wrote something to use Chrome to generate the PDF, and we couldn't get the page to look nice by using wkhtmltopdf's antiquated rendering engine. Is that our core business? Nope. But it's something we had to do because people want a PDF they can print out and give to their datacenter. No PDF, they can't give us their money. Incorrect PDF, and they get fed up and switch to a competitor. So I think it was worth the day or whatever I spent on it.
I would love to sell access to this API as a service. Sure, you can write your own. Sure, you can buy your own EC2 instance with a gig of RAM to run Chrome. It's easy! I did it myself! Or you could pay us, say, $0.01 per PDF generated and not spend $30/month on that EC2 instance and $200/hour on writing the service and maintaining it.
I think it's a great idea to outsource as much as possible. Some stuff isn't written yet, however, or it's bad. So you have no choice but to do it yourself. The people that have done it themselves and then charge money for it are how outsourcing is possible in the first place. (In fact, that's how EC2 got its start. I feel like that "not focusing on their core business" of selling books over the Internet turned out pretty great for Amazon.)
There are plenty of HTML-to-PDF web APIs though so if you want to spin a SaaS off of it you need to spend more time than just host it somewhere, e.g. some kind of market differentiation, SEO, work out pricing etc. If you're a lone developer sure, you can probably get to beer money profit quickly and kinda leave it there but your company needs to weigh the perspectives of a spin off against resources they remove from their "core expertise".
I would love to sell access to this API as a service. Sure, you can write your own. Sure, you can buy your own EC2 instance with a gig of RAM to run Chrome. It's easy! I did it myself! Or you could pay us, say, $0.01 per PDF generated and not spend $30/month on that EC2 instance and $200/hour on writing the service and maintaining it.
I think it's a great idea to outsource as much as possible. Some stuff isn't written yet, however, or it's bad. So you have no choice but to do it yourself. The people that have done it themselves and then charge money for it are how outsourcing is possible in the first place. (In fact, that's how EC2 got its start. I feel like that "not focusing on their core business" of selling books over the Internet turned out pretty great for Amazon.)