In my experience, not one student who received EMA in my sixth form centre put it to good use. They spent it on unnecessary things such as nights out, funding their shopping trips and in the odd case- drugs. It was very poorly implemented, money should not have been handed out so easily.
However, I understand that some students were reliant on it in certain circumstances where their household income is very low. Therefore it would be fair if they were given vouchers to go towards textbooks and such, and possibly partially covered transport costs; under one condition, they cannot access the sixth form centre in any other way.
Additionally, the ambitious, hard working students should be entitled to the above scheme. EMA should not have been given to students studying courses such as "Beauty Level 2", etc. as it's hardly educational. However, if it went towards an intelligent student from a low-income household considering a top university and they live in a location where part time jobs are few and far between, hopefully they will be able to pay back the benefit via taxation.
In essence, it was a system open to abuse. My main principle is that parents should not have children they cannot afford, though the child didn't choose it and if they are intelligent, then minimum help should be provided where there isn't a feasible alternative.