Bug is far from the worst typing. Sure it has a lot of shitmons. But that is completely different from how well the type preforms on its own.
>The BEST move ever in U-turn
>Only three weaknesses. Extremely valuable resists in ground and fighting
>Unique offensive typing, being able to hit dark and psychic types for SE damage.
Just look what happens when you give the bug typing to an actual good mon like Volcarona or Genesect, bam! Instant OU and uber.

The only true shit typing in the game is grass.