Sure, it lets you build a website in a jiffy if you know how to use it - but it takes away the personal touch and the expression of the designer in a way that tends to hurt the overall impression from the page.

I would posit that frameworks in general allow you to more quickly focus on those more personal and expressive design elements by cutting out a lot of foundation CSS that goes into a every project. For example, every project is going to need to be responsive and will more than likely be grid-based. Bootstrap has that all ready to go for you.

It's the same reason people use normalize.css rather than doing that all themselves: it's necessary, but unnecessary for you to do yourself if there's a template their for you to use.

If I start a new musical composition, I load my template. It has all of the thing that I use in every project I make: audio busses set up, favourite instruments loaded, effects plugins ready to go, session markers in place... Bypassing all of that each time I start a new track is not taking away the personal touch and expression of my composition. On the contrary, it gets me focused on it faster by having mundane but necessary processes already done.

Or take this exact web based tool I'm building. It will give the user quick access to information that would otherwise take considerably longer to work out by hand. But that working out isn't a creative or design based process, it's just necessary ground work. It's once you have that ground work done that you can use the results to do something personal. Is that not analogous to a framework?

Granted, Bootstrap goes a bit further than that and offers more design based components as well. But you can, and I have, customised those things with your own custom CSS. Furthermore, you can choose which parts of Bootstrap you want to use so it's not like it's all or nothing. You can even go and find a different, more light framework such as the one veen mentioned if it's found that Bootstrap seems to impose itself too much upon one's creative decisions.

Now I can't argue against your enjoyment of doing the HTML/CSS by hand each time. That's a personal thing and that's cool. But I'm looking to build websites in the way that professionals do. And I'm certain that every agency and web design house in the world will be using a framework for every project they do, whether it's Bootstrap, their own custom made one, or something else. I just don't see a reason not to use one unless you're specifically wishing to show off your front-end chops or practice concepts.

Also, one last point is that websites, especially one like mine that's meant as a tool, are required to have a standardised user experience. Users expect websites to functionally basically the same and that should be catered too as it allows the user experience to flow smoothly. An industry standard framework allows me to achieve that faster.

Though at the end of the day, I've only been doing this for ~3 weeks, so I'm still finding my footing. Perhaps the above sentiments are misguided. But If I want something where I value my own personal expression above all else, I will compose music.