Bootstrap does not cost anything, and the script portion is not really
scripting in the sense of running code on the user's machine, it is
jquery that allows modifying your own page to do things like expose and
hide elements when needed. Unless something has changed in recent
Bootstrap, the scripts are not required for basic functionality.
There are other tools like Bootstrap, but I forget the names of them. All
of them have the advantage of creating pages that look modern, which
means they look like what users expect.
But using them is certainly not required, and if the pages are for you,
then it doesn't matter at all. But if other people are using them, you
should still look at things like breakpoints, white space, appropriate
contrast between colors for visually impaired users, and coding elements
that make accessibility easier.
Microsoft uses 640 and 1080 as their breakpoints, yielding three
different 'page' sizes. These sizes seem to be in line with most devices
and most expectations.
One quick example of the benefits of a tool like Bootstrap is in menus.
It is first of all, quite simple to create a menu in Bootstrap that both
looks and behaves in a way that will be familiar to any user, but that
also collapses away to a button on a small scree where there is no room
for it. This is not only the best behavior, but the expected behavior.
And it is *really* annoying to hand code it, especially if you want the
same menu code to work across a variety of menu sizes based on the
content.
--
This above all, to thine own self be true And it must follow, as the
night the day, Thou canst not then be false to any man.