As Reinhold points out, knowing the meaning of words helps to memorize them. Knowing the original form (with diacritics) is a great aid e.g. during dictionary lookup of words that have unknown or uncertain meaning to the user, or just look unfamiliar without diacritics.
Using the words without diacritics is then a simple choice left to the user. Multiple Hungarian words can have the same form without diacritics. To include only one of these words in the list allows to keep the strength (entropy) generating from the list when using words without diacritics.
Also, it is easy to auto-convert to a diacritic-less form, while the other direction is ambiguous due to the above mentioned reason.
Note, that lists for other languages, e.g. Czech, are also provided with diacritics.