Interesting question. Bootstrap isn’t a tool to just get things done. It still requires you skills and codings. And when you’re building some big project then doing everything using raw html,css,js will be quite hard for you and building your own template framework will not be a good idea because you can mess things up.

And if you want to survive in the web design world. I suggest you to learn bootstrap and other things that you consider “a type of laziness” once you start learning them, you’ll notice the difference.