hand made, on the spot, inexperience ( not thousands but maybe hundreds ?)
hype, nervousness, sitters figgity, and not being digital all make for imperfect plates
i don't mind imperfections, and the whole wabbisabbi aesthetic, i can see how some people do
and would probably believe that the imperfections &c detract from the portrait ...

not all modern tintypists work is like this, some ( kerik, bill schwabb, giles clement, andrew moxom, photo booth sf and oodles of others )
are able to pour stunning perfect plates ...
but that takes hours and hours of practice and when you do anything over and over again you get better at it ...

i pour dry plates from time to time, and that is another thing that seems like it would be easy, after all commercial plates where often hand poured in the early days,
but it takes tons of practice ...

ymmv