The reason people hate Vegeta is because of his resting bitch face, rather than anything to do with his character.
Throughout the entirety of his role in the Dragonball series Vegeta has been nothing but noble.
Things that are regarded as selfish and vain about his character on anyone else would be considered quirky.
Apart from when he had no choice, Vegeta has always had his moral compass perfectly centered.
Even when he competes with Goku to be hte strongest he explains that his motivation is to be strong enough to protect others.
By all rights he's a truer hero than Goku, but the writing in Dragonball sucks so he's used as a villain.
He's a perfect example of the audience reading a book by its cover.
When you realize that then things like when he cries about Freiza destroying his family or when he performs his goofy dance scene don't seem out of character at all.
Vegeta isn't so much moody as he is focussed, which can apear as though he's very stern or serious.
Saving the people you love is a matter of great concern and should be treated with a manner ready for the situation, the guard up and alert.
Goku by comparison stumbles through events having plot granted abilities while he takes saving the people he cares about almost like a game.
The plot often explains that Goku has trained endlessly but character-wise it doesn't make sense since Goku is more likely to get distracted especially if food is involved.
Vegeta by comparison is more likely to take things seriously and spend a lot of his free time training rather than being distracted by anything else, including family matters.
It's also been shown that Goku despite caring for his close friends and family, fails to see the bigger picture and sometimes doesn't care that many strangers have died.
By comparison Vegeta take the concept of potentially many strangers dying premptively very seriously and its shown to affect him on an emotional level.
You can't say "Nah, Goku did more training, you didn't see it though, it was off screen." as an argument for plot.
The reason why is because if you were to play out that very scene realistically Goku wouldn't stay dedcated to his training at all, it's not his personality since his ignorance is an actual selling factor of his character when it's used for comedy.
That's not to say a hero has to be serious all the time but Goku is so far in the opposite direction he's less likely a main character plotwise than even Satarnsan.
In fact the writer of Dragonball seems to dislike the very characters with the correct attitude towards saving the world.
Tien is very dedicated to combat but dispite his actually rather practical skills he loses often because the writer says so.
The writing in Dragonball is absolutely awful by the way.
Just for 1 thing, there is no real way the characters in the show exerting the energy shown in the show could have destroyed every cell in Cell's body.
Even if you summise that they could, Goku's attack is much more likely to have done so than Gohan's since Gohan's move should have propelled Cell away from the blast.
Then there's the issue of auto instinct. It's quite literally the very first thing you're taught in martial arts.
If Goku had to learn that to win in the end that means that this entire time he's literally learned nothing from his training and won just because the writer demands it.
Essentially when Goku becomes a god he's simply earning his first belt, rather than becoming a master.
Many othr characters in the series have been shown doing exactly what it describes including characters from the original Dragon Ball, which includes Tien, Krillin and Yamcha, the latter of which is the first to be described as using that exact technique, members of the Gyunyu force, Kid Buu, various demons, champions of other universes and of course Vegeta.
In fact if you pay close attention, Vegeta uses that for almost every one of his attacks, including his regular attacks, special moves and qi blasts, most notably his Big Bang attack does not.
It's almost like the writer first looked up cool martial arts stuff and stuck that in there and then many years later actually started learning martial arts legit and decided to include his knowledge.
Whadda ya know about that? That's exactly what happened.
Freiza it seems is the only villain character NOT to use that technique, which is truly bizarre to be honest, especially since he kills the king of the sayans effortlessly and that are specifically stated to use this very technique.
Just thinking about that logically, how on earth are Freiza's reflexes faster? Oh i kno why, plot reasons.
Dragonball is clearly written on the fly, they start writing with very little understanding of pretty much everything to begin with and just keep writing without any plan of what to do in the end, any establishment earlier on of anything that could be useful later, any development of any ideas that could be useful throughout or even an understanding of the tools they have at their disposal at any given point.
Essentially the plot of Dragonball sounds like the ramblings of a raving derelict, rather than having anything that resembles structure, things happen because the writer says so, they are resolved because the writer says so and there is always a new tag along to that that needs to be solved in a future episode because the writer says so.
It almost makes the anime seem rather pointless.
Essentially, watching a compilation of explosions from movie footage to heavy metal rock music would have the same effect. It's just as action packed and lacks the same level of any real semblance of an idea what it's doing.