Arelith

Intimidate eats up a turn for -1 AC to everything, or -2 if you succeed by a lot. There may be situations where this is worthwhile, like if you're fighting a huge dragon and you know you're gonna be there for a while. But generally I find just hitting things to be way more useful.

I'd like the penalties to be harsher, eithet a worse AC penalty or additional penalties of some kind.

Intimidate is meant to serve party-centric play versus taunt's solo capabilities.

Both lasting the same duration is the greater issue than how weak the penalty might be perceived. The math would likely show that due to the lower AC penalty you wouldn't be doing enough total damage to justify its penalty duration being the same as Taunt's.

It was specifically made weaker to not make barbarians stronger.

Which unfortunately means that now Intimidate is a terrible investment for everyone except barbarians.