Even though the Buu arc was the beginning of the end, there was a silver lining to most of the asspulls unlike Super.
Super Saiyan 3:
Why it's bad - Asspull obtained off screen
Why it's not as bad as Super - Gave Vegeta a reason to be pissed off again, was a different design other than being recolored hair. Technically several years HAVE passed.
Goten and Trunks can go Super Saiyan:
Why it's bad - Super Saiyan is now handed out like a fucking gift voucher to every last surviving member of the Saiyan race now like it's not a big deal.
Why it's not as bad as Super - At least we knew Goten and Trunks to a degree and they had on screen time to develop as characters.
Why it's bad: Ultimately useless plotwise and brings out the worst in Toriyama writing ability
Why it's not so bad: New technique that gave us more possibilities and is the ultimate fanwank.
Gohan's power up:
Why it's bad - Gohan gets handed another power up without working for it, immediately fucks up with it in the most humiliating way,
Why it's not as bad as Super - Gave us the potential of having a different line of powering up other than going Super Saiyan and changing hair colors. Gohan wasn't as excruciatingly pathetic yet.
Nothing bad about 18 in Buu saga, was probably the most entertaining character.
Dragon Ball Super: Whoops we just sucked all the personality and likability of the character out of her once she started fighting in the tournament.
There's a lot more reasons why the Buu saga is bad, and reasons why even if they're bad, they're still not terrible compared to Dragon Ball Super.