The same thing applies to computing as to anything else. Nobody want to
drive an old car or watch a small B & W television. People want something
that is current.

Everything on your computer is bigger than it once was. My first computer
had 64K with a monochrome moniter and a 5 /4 inch floppy disk that stored
128K. Compare that with today's cell phones. When you ask something to do
more then it requires more.

You assume big means bloated and it can, but it does not necessarily follow
that this has to be the case. You can still write tight code and Linux has a
history of doing this. The kernel has remained much the same in recent
years. You can still run Linux from foppy disks. What has changed is the
support modules. There are more modules because more is happening. People
have more drives, more devices, more of just about everything.

If small is your thing then you can still do it by compiling just what you
need and running a stripped down OS. You should look at Arch or LFS. Don't
assume that Ubuntu is all that Linux can do. It can be small, but most
people choose not to run a bare bones system.