That would be very nice to have. In general, CCP ought to put some work into renovating chat functionalities, moderation functionalities, mailing list moderation functionalities and so on.
It would be nice to reduce the spam but I don’t think it would be effective. You can roll a new Alpha and fly them to Jita in a couple of minutes and I have no doubt most spammers are using disposable Alpha accounts. They used to use disposable trial accounts.
The best solution is to ignore them - monitor a different chat. The reason spam exists in-game and in the real world is that it works - they make a lot of money from people who believe Jita local is populated by philanthropists.
If you ignore local chat in Jita, the probability of missing anything useful is vanishingly small.