Because this is our mother tongue. Most of us, unlike in the beginning of 1990's, can speak Hebrew these days at least on the level of the majority of the Israeli general population (some of us even speak better than many of those who were born to Hebrew-speaking parents). If you feel uncomfortable when people speak next to you a language you do not understand - that is legitimate and understandable. Many would call it rude, but hey, aren't we in Israel, the country where rudeness is a social norm, especially towards those who do not belong to your little clan? And regarding the Moroccans, or Romanians or any other ethnic group - timing is everything. If those groups came here at the end of the 20th century and in the numbers of the Russian immigration, believe me, all of them would be speaking their native language (as their elders still do). I hope I did shed some light on the issue as you requested, though something tells me that it's not exactly what you were after. In the end of the day, I am sure this will not change your attitude towards the Russians or any other ethnic group or social matter, because your opinion, as the opinion of every single Israeli (including Russians) is the most correct one.
Law expanding definition of terrorist activity passes first Knesset reading (Haaretz)
from the article: There is no such thing as Russians in Israel