No it doesn't, that's literally one case where a novice Landon was doing risky moves in front of his opponent. And yeah, defending in certain way can leave you vulnerable to certain attacks, just like in boxing you can easily eat an uppercut with that sort of movement. Vitor pulled guard against Jacare which is a defensive move and got pounded doesn't mean that BJJ sucks.
Since when do boxers need to worry about kicks or bats? Might as well stop watching MMA then because by going into fights without weapons they're leaving themselves open to being stabbed.
Because limiting the rules to hands only gives boxers more freedom of movement and provides exciting 10-12 rounds of tactical warfare or a battle of endurance and will. The results in an aesthetically more pleasing sport which is also more technical, more demanding and gives a better indication who is the better man, the better competitor and the better athlete between the two people who participate in the sport. MMA is the pop music here because it's less technical, less tactical and more of a lottery. More people can understand it and it's also great for this short attention span generation because the fights aren't that long.
Limiting a duel to a set of specific rules is the most ancient of human traditions. Even real warfare has rules. Boxing is essentially pure fighting when you remove all the bitch moves, it's a gentleman's sport.
If boxing didn't exist MMA wouldn't exist today either. The only reason why it's not banned and underground is because MMA pioneers used boxing (an established sport with 100+ years of history) as a reference, claiming that their sport isn't more dangerous than boxing. Because boxing is culturally established the public accepted MMA.
Also, it was only after UFC was taken over by BOXING people like Dana White that progress was made because non-boxing people are clueless when it comes to promoting fights. That's the reason why all other combat sports can't even sustain themselves only boxing and UFC (thanks to a boxing aficionado Dana White) make real financial profit and real big money fights.