I fully agree with your points mentioned above, but have several points of my own.

First, it may not be ignorance but more of denial, refusal to accept that there is an inequality we should overcome.

Next, with regards to the need for thick Indian accent, while I believe true humour should not be build upon racism, I have to point out that what drives director Neo to film is simply money and box office success. True, it may be a little distasteful and insensitive, especially in Singapore where we were taught to be racially harmonious since young. However, the box office results shows otherwise. This leads me to have the following thoughts:

1. If we were against racism, shouldn't we have condemned any form of racism in Jack Neo's previous films, or even boycott them? Thereby preventing sequels Ah Boys to Men 2, 3 as well as this audition which led to the whole saga. Are we truly against racism, or merely using this word at our own convenience?
2. If the film has to be extremely realistic and factual, it will probably be known as a documentary, which not exactly Singaporeans' favourite. Thus drawing the line between profits (in terms of box office) and reality is a dilemma; film, with a recipe proven to work, for profits and get criticised in the process or film at your own expense to produce something that possibly neither anyone recognise nor appreciate.

Honestly, I think this saga is nothing but free publicity for the movie even before it has started filming, at least before something changes in our views about racism and our actions. Raising up controversial topics is good, but only when something is done thereafter.

And I believe that we Singaporeans, just like my English, still have a long way to go.