To spread Arab culture and attempt cultural domination...

Salute to all the anti-arab-booty clapping peeps in Iran, Somalia, Turkey and all other Muslim majority nations for retaining their own indigenous language though. Fardowsa is probably proud!! R.I.P to the endangered Berber and Nubian culture...
That is not the case. God chooses what he wants and does as he pleases. Arabic is similar to all other languages mankind speaks and spoke. Jesus spoke Aramaic and Hebrew. Muslims do not question a prophet's ethnicity and language but believe in all because their message was the same.
To someone who believes in God, they would not care what language or race his messenger belongs to. People who don't understand God are the people who are obsessed with race and linguistic differences when it comes to Religion.
The attitude of people who ding Islam for Arabic are the people who are okay with supposed son of God painted as white and with blue eyes even though obviously that is ridiculously stupid and they know it. These individuals and societies want God to be racist. That is how extreme they went with ethnic obsession.
Muslims embrace all prophets of God. Regardless of race and language.