why should women have less share of Inheritance (4:11), or why there must be two female witnesses equaling the testimony of a man (2:282)? why is the act of polygamy allowed for men (Even if it 's under special conditions)? (I certainly don't think it should be allowed for men and women).
My simple short answer :
1 - Inheritance issue, because men have to provide sustenance (food, shelter, cloth, and all other expenses [and its obligatory] ) for the family at all time (there are exceptions of-course like husband is ill or dead or unable to work).
and its obligatory for the husband he has no right to say no.
Wife, on the other hand, takes less in inheritance but its all hers. she has no duty toward the family at all - No Nothing At All. Period. no one has the right to force her to spend that which belong to her except by her permission.
2 - Witnesses, other forum members would help.
3 - Polygamy, women are always more than men due to large number of male deaths during wars, accidents etc... so if every man gets one woman in that exceptional case then what are the other women going to do and you know they too have desires so they will have secret immoral illegal sexual relationships (with who? yes you are right, with the married men).
women cannot have more than one because men are aggressive over their female partners and putting it short they will kill (when got the chance) any other man having relationship with his partner. forget about 3 other men - there will be WAR.
there are detailed answers to those questions which will further enlighten you.