The pressure inherent to any TV show ending is huge. After all, audiences have spent years and years watching the story play out and, when it finally comes to wrapping things up, fans aren't quite as forgiving as they might be with a motion picture. Which after a mere two hours feel a lot less consequential than a lengthy TV saga.
You're looking at a vast and epic construct of more than 50 hours, in most cases, going on the notion that most beloved shows run for at least 5 series, comprising of anywhere between 10 to 22 episodes per season. No wonder people get so irked when said show fails to culminate in a way that feels justified.
Not that that's an easy task or anything; you have to tie everything up in a way that seems fitting and yet manages to be unpredictable at the same time; characters must live or die; couples must come together together or break apart; a few curveballs and some ambiguous notes are expected to be thrown in for good measure, too.
Yes, it's tough to find the "perfect" ending because everyone expects something entirely different. In the cases of the following 10 TV shows, though, some of which were deemed unsatisfying, the alternate endings proposed or revealed by the showrunners would have probably made a lot more people a whole lot happier...