In older times, with the simpler BIOSes that where available then, you
needed things below cylinder 1024 (or something). Having /boot as the
first partition and its size extending not beyound that limit, made
booting after upgrade safer. I guess that argument is moot today,
even if it gives you a warm fuzzy feeling, that you are safe even if
you occationally would plug in your disk on an old motherboard that
you happen to have handy.
A. Soo, there was formely at least one reason.
B. you might have a few systems using the same /boot, eg. for testing.
There are a lot of handy things you can argue for if you mention
testing.
C. Who cares.
With todays disk sizes you can have /boot sufficiently large for how
many kernels you want to have without hampering any other partitions.
So, what is the problem, what does it matter if someone wants it for
whatever reason. In the end, as time goes by, your disk will be too
small for your system use, and your processor will be too slow etc.
so you will have to replace things that don't gives you what you need.
And, it isn't good economy to chase every perceived flaw.
D, As Martin wrote, you can use a simpler fs type, eg. ext2 or even
vfat to comply with other things, eg. booting other types of systems.
(Since you already might have an efi partition, why not put boot there.
I have not tested that but it could be a possibility.)