Some years ago I went to see a greek newspaper and was very astonished: many accents and breathings—comparing to the ancient Greek studies I have done—had disappeared from the script. This is in that way that I became aware of a governmental reform of the Greek script.
I did not learn to speak modern Greek but I cannot figure out that all the polytonic inflections of the spoken Greek language had suddenly vanished and that the diacritical marks in the script became of no use to read a Greek text!
Moreover, I am still wondering if the homonymy problems created if you suppress the accents from a Greek word are no more existing. This was pointed out by all my Greek professors with a great stress: “be careful, do not confuse: ἡ, feminine definite article, with: ἥ, feminine relative pronoun, with: ἤ, or, better than, with: ἦ, I was. Do not confuse: εἶναι, to be and: εἷναι, to have been sent (from ἵημι); ἰέναι, to go and: ἱέναι, to send.” The list could be longer! Do similar examples have totally desappeared in modern Greek? I doubt!
Diacritical marks were made to help the reading and everything made for this purpose is very useful. The French Academy pointed out once that, contrary to a legend, capital letters also were to be accented in French to help the reading; you must write “École” and not “Ecole”!
But diacritical marks are not only for the reading, they are also the memory of the language: long long time ago some letters have disappeared from the Greek script but they have left some marks to the words; for instance οἵδα (I knew) stands for a former ϝοίδα which makes clear that this word is the “same” as the Sanskrit veda. I cannot imagine that some accents, the effect of which is almost imperceptible in the French spoken language, could vanish one day, for they are the mark of a disappeared letter like in “hôtel” or “hôpital” where the circumflex accent stands for an old “s” which you still can find in French words like “hospitalité”, “hospice”, etc. And how to explain now “rhododendron”, if you write ρόδος and not ῥόδος? Greek is not only the language for Greek people, it is also a big part of the European culture!
I went to become a sanskritist and learnt the texts of the Indian culture. In the ancient times, old wise men declared that a script must reflect all the possible phonems of a language to be a suitable script. And they built alphabetic scripts for Indian languages—they probably built the alphabets for all languages from South East Asia—: around fifty letters and rules to combine them with ligatures in order to accomplish what they had decreed. Still nowaday, Indian languages use these scripts and you can often read on the shop signs some transliterated words from english: while reading, you can hear all the characteristics of the Indian people accent when they speak English! The aim of the old wise men has been fulfilled and nobody complain against the fifty letters and ligature rules...