It is not cool, it is just easy. No effort to understand a problem even less
effort to understand is there really a problem...
So people who talk on this topic aren't thoughtful? Sure some aren't, but that's the same for any topic. You're cherry picking there, it doesn't stick.
I'm currently working in an organisation that specialises in behavioural science, we have the actual data on this. If you look at the studies there's overwhelming evidence to support an opinion that these problems are real. Women and different ethnic groups are treated in different ways with regard to things like hiring, performance reviews, etc. and there's a significant enough difference that the system could be defined as racist and sexist, even though no individual feels that they themselves are racist or sexist.
If you want citations... here are some just relating to the field of gender and employment...
Female job applicants with children considered less warm, likeable and committed than male applicants with children. Successful mothers penalized for promotion, hire, and salary (Benard and Correll, 2010). Women expressing anger more penalised than men (Brescoll & Uhlmann, 2008). People in gender-incongruent roles penalised more heavily for mistakes (Brescoll, Dawson, & Uhlmann, 2010). Voluble women perceived as less competent and less suitable leaders, inverse true for men (Brescoll, 2011). Men who work for women in stereotypically male dominated fields accorded less status and lower salaries (Brescoll et al, 2012). Women who succeed in male-dominated fields percieved as not likeable (Heilman et al, 2004). Students question the competence of female teachers who evaluate them negatively, less so than male teachers (Sinclair & Kunda 2000). Female students seen as less competent than identical male students, offered lower starting salaries (Moss-Racusin et al, 2012)
... even some words are taboo the concepts behind them are inaccessible
so people are not able to think about them. This results in people not
really understanding what racism is...
This point is broadly right (you have cause and effect inverted), but it doesn't just apply to "SJWs" as you're implying. People in general don't have a vocabulary to talk about racism and sexism. People don't typically identify as racists. They think "racists are 'bad people' and I'm a 'good person' so I can't be one", but in fact race is a more complex beast in the 21st century so we need a more complex vocabulary to describe it without triggering defensiveness.
Using 'social justice warrior' as a snarl-word is a sign that you feel defensive and uncomfortable. But that discomfort doesn't mean the 'SJWs' are wrong, it just means we as a species don't have a good set of verbal tools to communicate with each other about what's happening.
I'd recommend reading this, it's long but worth it if you actually care about this topic:
http://www.huffingtonpost.com/good-men-project/why-its-so-ha...