Related question: why is Iran okay with the Houthis targeting random international shipping?
Continuing to poke international commercial shipping will obviously trigger a response. No one powerful, even China, wants non-military ships being attacked.
So they're risking substantial damage to Houthi power for... what?
Tying up naval capacity? Eh. Temporarily. And with minimal effect on Israel/Palestine.*
Boosting the price of oil? Maybe. But doesn't seem to be doing much yet.
At Russia's behest? Maybe. General chaos elsewhere and tying up ISR assets benefits Russia.
* Would become much more relevant if Hezbollah enters the war.
It could also be an internal thing for the Houthis that we (certainly I) don't know about. Being able to say "We're standing up to Israel and the US" could be big for their credibility in Yemen. That is pure speculation however.
(Trump was tougher against Iran but they feel they can survive it. What's important is that the Mullahs read all the press arguing that Trump is a danger to the American republic itself and take it into account. How often does one get a chance to seriously harm such a powerful country like the United States? For people whose call is 'death to America', this is a one time opportunity, which at worst won't work. These people are compulsive gamblers especially with assets they can afford to lose like the Houthis.)