Initially they probably were. But since things have calmed down a bit and it's clear that Ansarallah are only targeting ships supporting the genocide, other ships are getting through unharmed.
Yeah but then they started operating with the assumption that they could charge those prices and some brain genius suggested taking the old route but charging the same (i assume).
The more probable answer is that labor costs a lot (if you wanna pay out big bonuses to the c-suite instead of staffing a ship with more than a skeleton crew), bunker fuel costs money and going around the Cape means they're spending more time between ports and using more money to do it. Them taking longer probably also risks contracts due to JIT supply that we run with these days.
To speak more to labour costs: Almost all innovation is shipping is driven by the question "how can we have fewer people doing the same task". You have to be pretty self reliant working on ships these days, because there's rarely a lot of people overseeing you, even if you're an FNG. Or so I'm told.