Many words in places influenced by Arabic (or other Semitic languages) take similar forms, in this case mu_a_i_d (een is plural). Arabic has a triliteral root system and this form is a way of structuring a root to indicate the person who does the thing the root refers to. I don't know if Tamil was influenced by Arabic; in this case it could be an utter coincidence.
six weeks ago I would have regarded the idea of doing this as inimical to the principles of free discourse and debate that I feel are fundamental to democracy and indeed to small-l liberal civilization in general.
now I find myself wondering whether my principles are being contaminated by the immense personal anger I feel, or whether perhaps my principles weren't as rationally derived as I had previously believed.
This is a good idea, and one that I could certainly have used when learning Arabic— but its real utility is not for Modern Standard Arabic- it's for 'amiya/3amiya (spoken Arabic), which, to those not in the know, differs from region to region and is vastly different from both written and spoken forms of Modern Standard Arabic.
As someone suggested above, learning Arabic script is the first-- and smallest--of many challenges for those trying to learn formal Arabic.
There are few good systematized sources available for people trying to learn spoken Arabic, particularly if they're not particularly interested in reading the news or classical texts. I'm thinking of aid workers, diplomats, vagabonds, whatever.
A system such as this has great utility to these people— except it already exists in much of the Arabic-speaking world, particularly the Levant and Egypt, where numbers are used to represent sounds not found in the Latin alphabet.
For example: "You will speak Arabic soon" (Levantine) - "إنت رح تحكي عربي قريبا" - can also be rendered as "inta ra7 ti7ki 3rabi 2areeban". This makeshift system is used widely in texts in Lebanon and elsewhere. Utilizing this existing method will be easier and have wider applicability.