Ok, I've been following the controversy about removing the "Arabic" from the naira for some months now (see the following articles and here and here and here, and I'm annoyed by the lack of historical knowledge behind this decision....
First of all, it is NOT Arabic that appears there in that beautiful flowing script at the bottom of the N500 pictured above. It is HAUSA written in AJAMI, which is the name for the Arabic SCRIPT that was brought to the region that is now northern Nigeria probably around 900 years ago. Therefore, to take the "arabic" off because it is a foreign imposition is just nonsense; it precedes Roman script in the region now called Nigeria by about 800 years. Hausa has been written in ajami script for at LEAST since the 17th century (See John Edward Philips article "Myths of Twentieth Century Hausa" also "Hausa Orthography in the 20th century" or Hausa Roman Orthography: Reform). And for a far longer time, historical records were kept in Arabic (just as official business and writing in Europe was often conducted in Latin). So is Arabic even a "foreign" language? (Here is another link to the importance of ajami to the study of history)
Second of all, Hausa in roman script was introduced by Lord Lugard at the beginning of the last century, because he made Hausa the official language of the army (according to Philips because it was already widely spoken as a trade language from the north to the middlebelt where he was trying to recruit soldiers) and wanted his colonial officers to have an easier time of learning the language... and apparently it would have been too hard on them to make them learn ajami... (I know... I started learning ajami and have forgotten it all... but plan to start again.) So, really, if one is worried about foreign impositions, the roman script is a far more recent imposition. And the anxieties that pushed the colonialists to make the change to writing Hausa in Roman script seem to be the same anxieties that propell this "nationalist" decision to remove ajami from the naira. Does that mean roman script should be tossed out and ajami reinstituted. No. But does the fact that the colonizers preferred Hausa mean that all Hausas colluded with the colonizers? Any more than the warrent chiefs mean that all Igbos colluded with the colonizers? Obviously not. The issue with the naira is... what of the people who only read ajami? which brings me to my third point....
Third of all (not proper grammar I know), my impression is that the ajami on the naira was to communicate with those people who were literate in ajami but not roman script. There are still quite a few people in the north who recieve Q'uranic education (and not government education), for whom the ajami lettering is helpful.
I understand the argument that it is not fair that Hausa is the only non-English inscription on a national currency, but then Hausa is the only language that has another script. Now that there are Hausa, Yoruba, and Igbo roman inscriptions, what does this say to the other 400 or so languages in the country? Too bad for you?
For more information on the introduction of the roman script and colonialism see John Edward Philips' Spurious Arabic: Hausa and Colonial Nigeria