Most of the elves are cheerful, so why is Bernard so uptight? Well, given his high position and the legacy status of Santa, he's likely gotten impatient with giving the same spiel over and over again, in addition to becoming more and more jaded every time another Santa goes missing, which would no doubt be worse if he thought of the Santa in question as a personal friend.
The previous Santa gave a little wave to Scott right before disappearing, and the Santa Clause says that he who puts on the suit must do the job until no longer able to, "by accident or design." Perhaps that Santa was ready to pass the job on, and gave the elves plenty of advance notice that he intended to go out with a bang and that someone else would be returning from his flight that year (or maybe that little wave meant "I'm done for. Good luck, new guy."). Any angst the elves felt would already have been worked out by the time Scott showed up at the North Pole. The Santa Clauses confirms this is true.
A gay man, or one who'd simply be happy single, wouldn't be able to stay as Santa Claus for more than a few years unless they entered into a marriage they didn't want.
How many people before Scott have played the role of Santa, and how many times has someone been replaced after falling off a roof or getting seriously injured in other ways that tragically ended their career as Santa? Of course, this is assuming there was more than just one Santa beforehand. The elves are pretty quick to accept that Scott's the new one, right after the last one's death. How many times has Santa passed that they're that used to it?
A lighter explanation: perhaps any Santa who "died" was just warped back to their home without any memories of taking on the clause?
The Santa Clauses reveals that there were at least half a dozen Santas, all of whom were magical nonhumans, before Scott.
If being Santa makes Scott immortal, doesn't that mean he'll eventually outlive his son Charlie? Charlie's younger half brother Buddy would end up watching his big brother grow old and die while he presumably lives on to take over as Santa one day.
What happened to the previous Santa's wife? Did she lose her immortality and just crumble to dust when the previous Santa died? Risking your own life is one thing, but the realization that (after a certain number of years) your wife is doomed to die with you would eat at you and make you paranoid.
Even if she didn't die, he had to have a wife thanks to the Missus Clause. There's no trace of her there when Scott arrives the same night the the previous Santa died. Immortal or not, the previous Mrs. Clauses are quickly torn away from their old homes like employees who got fired and replaced.
Perhaps he wasn't Santa long enough for the clause to kick in. After all, the guy really doesn't seem to be too good at his job. In the second film, Scott is stated to be one of the best Santas ever, if not the best. He takes great care to actually give people what they want as opposed to prior ones who, as evidenced by Laura and Neil's stories, didn't really try.
The Santa Clauses reveals that both the Missus Clause and the other Santa Clauses were created specifically for Scott and his family once he took on the mantle of Santa. This implies that Carol is the first Mrs. Claus.
Weren't the elves ever concerned about their production streams potentially having a negative impact on the economy (i.e. money-making prospects for businesses and individuals) down on Earth?
Perhaps Santa only delivers gifts that he knows parents didn't already buy for their children.
Fridge Logic, Fridge Horror and a smattering of good ol' Squick. Judy (who in-universe is Really 700 Years Old) mistakenly thinks Scott is coming on to her. Does this mean a previous Santa had a fling with an elf? AIGH!
How about having your entire life taken away from you just because you put on the wrong clothes?
This is a binding magical contract with no less than three ironclad clauses in it that are activated by putting on a coat, right? OK. Now...who's enforcing this? What all-powerful being created this? Who demanded it? Is it God? Assuming there is a God around, why would they need to create the Clauses? Moreover, if it's not God, or any gods at all, then how long has this been going on exactly? Judy said it took her twelve centuries just to perfect a cup of cocoa, so it's at least that! If that's the case, it could have started with St. Nicholas (a fourth-century bishop), but that would mean that "God" is just an allegory for "magic(ks)." That would also explain how all the elves are basically just children that can live for thousands of years.
Back to the original point of who's enforcing this contract - in the first film, Scott questions what would happen if he just chose not to follow the Santa Clause. Bernard just guilts him into doing it, but what if that didn't work? In the third film, Jack Frost just turns Christmas into a parody, but what if there's a guy who just hates Christmas, puts on the coat, and refuses to deliver the toys, who doesn't care about how disappointed the children of the world feel, and just wants the holiday to die? What's stopping him?
This awful Santa would likely suffer from De-Santafication for refusing to follow the rules. Even Scott, who was acknowledged to be the greatest Santa there ever was at the start of the second film, was in danger of losing the job for not obeying the rules. A Santa who refused to even deliver the toys would likely have the position taken away from them in short order.
The Santa Clauses would later reveal the existence of the Mad Santa, who was apparently so tyrannical that he was imprisoned in a nutcracker, suggesting that it's possible to remove a Santa who misuses their power after all. The series would also reveal that both the Missus Clause and the other Santa Clauses were created specifically for Scott and his family once he became Santa.
